Many common European languages are better seen as more than one language. I have been studying this issue for years, and this is some of my preliminary data. It is not yet in a publishable form, but it will give you some idea of the concepts that I am working with.
Kashubian
Really two separate languages as opposed to one.
North and South Kashubian are separate languages. Speakers in the north can’t understand those in the south.
Cimbrian
Really three separate languages as opposed to one.
Lusernese Cimbrian, Sette Comuni Cimbrian, Tredici Communi Cimbrian (Tauch). Based on structural and intelligibility differences, the three dialects could be considered separate languages.
West Frisian
Really three separate languages as opposed to one.
Schiermonnikoogs (Skiermuontseagersk) is an archaic West Frisian dialect, poorly understood by the rest of West Frisian, that is spoken on the island of Schiermonnikoog. It is actually spoken more in the north of Groningen than in Friesland.
It is in serious decline since WW2 due mostly to immigration from the mainland. The newcomers arrive speaking a West Frisian dialect from Groningen, Vastewal. There are only about 100 speakers left. However, many others speak a “weak” Schiermonnikoogs. Courses in Schiermonnikoogs have been popular since the 1960’s, and there have been a number of publications in the language.
Hindeloopers is an archaic West Frisian dialect, really a separate language, that is spoken on the SW coast of Friesland in the town of Hindeloopen. It has very conservative phonetics and vocabulary, much of it from Old Frisian. Hindeloopers is slowly becoming more like Standard Frisian due to increased exposure of its speakers to Standard Frisian and immigrants moving to the area. It is hard for other Frisian speakers to understand.
North Frisian
Really five separate languages as opposed to one.
North Frisian is four different languages as far as % cognates is concerned. Mainland (including Halligen Frisian), Öömrang-Fering, Sölring and Halunder/Heligolandic. Also, Hallig is not very intelligible with other mainland varieties like Mooring.
Manx Gaelic
Really a living language as opposed to an extinct one.
There are now 2,000 people who claim to speak Manx. Some are raising their children in Manx.
Breton
Really probably five or six separate languages instead of one.
Vannetais is a separate language. It is not intelligible with Leonard, another main dialect. Spoken in Brittany – the entire area of the department of Morbihan (with the exception of Belle Isle and regions around the Faouët and Gourin): Valves, Pontivy, Lorient, Plouay, Guémené-sur-Scorff, Baud, Auray, Quiberon, Sarzeau and the commune of Finistère Arzano.
Further, West Vannetais cannot understand East Vannetais.
Leonard is a separate language, not intelligible with Vannetais. Spoken in Leon (Leon or Bro Leon), the northern third of the department of Finistère (Brest, Morlaix, Plouguerneau, Landerneau, Saint-Pol-de-Léon, Landivisiau, Ouessant).
Leonard is about as far from Vannetais as it is from Cornouaillais. Intelligibility between Vannetais and Cornouaillais is not known.
Cornouaillais may be a separate language due to its distance from Leonard.
Groisillon, spoken in the Groix, is reportedly hard to understand for speakers of other dialects. It may be extinct, but more likely there are a few speakers left. Breton reportedly has 77 different dialects.
The new Neo-Breton taught in the schools often can’t be understood by traditional speakers because it is full of borrowings from Cornish and Welsh.
Asturian
There are two languages – Eastern Asturian and Central/Western Asturian instead of one.
Leonese
There are two languages – Eastern Leonese/Extremaduran and Central/West Leonese instead of one. Extremaduran is intelligible with Eastern Asturian.
Aragonese
Navarese is not really spoken anymore or it is just a Spanish dialect. Benasquesque/Ribacorgano is a separate language in between Aragonese and Catalan. Far northern and far southern Aragonese cannot understand each other.
Gascon
Apparently more than one language. Aranese is apparently a separate language.
Languedocien
Apparently more than one language.
Auvergnat
Apparently more than one language.
Limousin
Apparently more than one language.
Provencal
Apparently more than one language.
Walloon
Walloon is four separate languages instead of one.
East Walloon – Barvaux, Huy, Liège, Hesbaye Liégois, East Liégeois, Verviers, Malmédy. South Walloon – Marche-en-Fanenne, Bastogne, Neufchâteau, Saint-Hubert, Bouillon. Central Walloon – Basse-Sambre, Nivelles, Rochefort, Dinant, Namur, Charleroi, Beaumont, Chimay, Philippeville, La Louvière. West Walloon – East Brabançon, Jodoigne, Wavre, Hesbaye Namur, Gembloux, Sombreffe, Eghezée.
Francoprovençal
This is more than one language. It may well be up to an incredible 24 different languages or even more.
Dauphinois, Jurassien, Lyonnais, Savoyard, Vaudois, Valdotan and Piedmont and are the major dialects, and all are probably separate languages.
Franche-Comte, spoken in Neuchâtel, Vaud North, Pontassilien, Ain, Valserine is a separate language.
Faetar is a separate language from Arpitan. It split off in 1400 and has undergone heavy influence from Standard Italian and Apulian. It has 1,400 speakers in two towns, Celle and Faeto in Apulia in southern Italy. Language use is still vigorous even though most people in the towns are unemployed or retired. A few work in the fields.
Bressan has some internal diversity. The youngest speakers are about 60 years old now, but there are still dialect associations that promote it strongly. Bressan was the main mode of communication here until the 1970’s. Bressan itself is probably a separate language.
Forézien is now almost extinct. Forezien is apparently a separate language.
Geneva, Fribourgeois, Neuchatel, Valaisan and Vaudois are the dialects of Switzerland, and all of those are probably separate languages too.
Valais has some of the strongest dialectal differentiation in the entire Arpitan region. Valais is divided into two large languages – West Valais spoken around Lake Geneva and East Valais spoken around Sion. Intelligibility is poor between the two poles.
In Valloire, Valmeinier and Valle Arvan at the far southern end of Savoyard, between St. Jean de Maurienne and Modane, a Savoyard dialect – Southern Savoyard – is spoken that is not intelligible with the rest of Savoyard. It is also different in Valloire, Valmeinier and Valle Arvan, but intelligibility among those three varieties is not known. Probably heavy influence of Occitan in this region. Possibly three separate languages here.
In Valloire, all persons over 60 use Arpitan as a daily language. St. Michel-Modana Savoyard is a separate language.
Valloire is a separate language. It is not intelligible with the dialect spoken in Albanne near St. Jean de Maurienne. Valmeinier, Valle Arvan and St. Michael de Maurienne also appear to be separate languages. The speech of Albertville and Chambery could be called South Savoyard. Dauphinois is still widely spoken in the villages around Villard de Lans south of Grenoble.
In the Savoyard area from Mt. Blanc to Geneva to Montreaux to Evian to Abondance, there is good intelligibility among dialects. This could be called North Savoyard. As one moves to the south, it gets harder to understand. North Savoyard and South Savoyard seem to be two different languages. In the Val d’Illiez area between Montreaux and Martigny, some Arpitan dialects are spoken that are very different from everything else.
Romansch
There are actually five or more separate languages instead of one. Each dialect is a separate language.
Upper Engadine: Puter, Lower Engadine: Vallader, Upper Rhine: Surselva, Lower Rhine: Sutselva, in between: Surmeiran. Romansh is actually 5 different languages, at least. Intelligibility is probably on the order of 80% or so, though testing might be nice.
Val Bregaglia/Valtellina Romansch (Bergajot) is an old Romansch dialect formerly widely spoken in the Val Bregaglia and Valtellina region of Italy. It is now only spoken by the elderly and a few younger people. It is mostly a mixture of Puter Romansch and Ladin with an overlay of Western Alpine Lombard Italian. It was the lingua franca in the region 100 years ago, but has since been replaced by Western Alpine Lombard Italian. Not intelligible with the rest of Romansch or with Italian. Some intelligibility of Ladin, some of Romansch, less of Ticinese Italian.
Bergajot is spoken in the Bregaglia Valley near Chiavenna and upwards towards Switzerland. It is more Italian than Puter Romansch, but Puter Romansch and Bergajot speakers can understand each other. This was probably the natural extension of Romansch to the south, but the language was never written down, and Italian was adopted as the written language, so what developed was a cross between Romansch and Italian.
Unknown whether Bergajot is a separate language or part of Puter Romansch.
Ladin
Ladin is a number of separate languages instead of one. Possibly 12 or more different languages.
Western Ladin includes Fassan, Gardenese, Novi, Nones and Solandro.
Fascian Ladin or Fassan Ladin: Spoken in Val di Fassa and variants in Moena and Canazei in the Fassatal Valley of the Dolomites. There are 8,620 residents, of whom 60-75% speak Lain as a mother tongue. There are two main varieties, Canazei Fascian in the upper valley and Moena in the lower valley. Heavy Italian influence. Fassan is Dolomitic Ladin. Spoken in Trentino Province.
Brach Fascian: Spoken in the center of the valley in Soraga, Pozza di Fassa and Vigo di Fassa. Intelligibility with Moena or Canazei is unknown, but may be nearly intelligible. Possibly not intelligible with Fiemmese Ladin.
Moena Fascian: Spoken in the lower part of the Val di Fassa. Canazei Fascian has problems understanding Moena Fascian. Spoken in Moena, Mazzin, Vigo de Fassa, Pozza and Soraga. Intelligibility with Fiemmese or Brach is unknown but may be nearly intelligible.
Gherdëina Ladin: spoken in Val Gardena or Gröden Valley, South Tyrol, by 8,148 inhabitants, 80-90% of the population. This dialect is close to German. Spoken in Bolzano, extremely protected. Gherdëina is described as “completely different” from Fascian, Anpezan and Cadore. Val Badia can understand Gherdëina but Fassa cannot. Part of South Tyrolean Ladin. Intelligibility between Gherdëina and Novi Ladin is unknown but probably good.
Nones/Solandro Ladin: spoken in Val di Non (as Nones) and with variations in different parts of the valley and the adjacent lower Val di Sole (as Solandro) in Trento Province just north of Trento and just west of Bolzano.
Nones has a lot of German words in it. Two different forms – Nones and Solandro or Solander. Solandro is spoken in Val di Sole, Val di Peio and Val di Rabbi (as Rabies). The last linguistic census of 2001 found that more than 7,000 residents in Val di Non and Val di Sole spoke Ladin. It is uncertain whether Nones/Solandro is a language of its own. Some say it is part of the Trentino language. Nones/Solandro is basically a Ladin dialect transitional to Trentino East Lombard. Often referred to as Anaunico Ladin. Val Badia and Fassa cannot understand Nones.
Intelligibility between Nones and Solandro is uncertain, but they are considered to be part of one language. There are two main dialects of Solandro, one in the lower valley and one in the upper valley. The lower valley has heavy Nones influence, and the upper valley is more conservative and has Celtic influences.
Lower Valley Solandro in the lower valley is spoken by 4,000 people in the towns of Caldes, Terzolas and Male and has heavy Nones influence.
La Montàgna Solandro is very conservative and very different. It is spoken in Termenago and Castello in Pellizzano and in Ortisé and Menàs in Mezzana. It is very conservative and has almost nothing to do with the valley dialects such as Pellizzano and Ossana.
Pellizzano-Ossana Solandro is spoken in the towns of those names and the two are very similar. This dialect resembles Eastern Lombard. Many miners came from Lecce and Como in the 14th Century to work in mines here, and this accounts for the Lombard influences on the lect. It is spoken by 500 people in Pellizzano and 800 in Ossana. May be intelligible with Vermiglio Solandro.
Rabies Solandro spoken in the Val di Rabbi is one of the most conservative forms of Ladin in existence.
Nones has 30,000 speakers, but there is some debate over whether it it Ladin or not. Solandro is also under question about whether or not it is Ladin. It has 15,000 speakers.
Central Ladin: (transitional to Alpine Venetian).
Val Badia-Marebbe Ladin (Maréo/Badiot Enneberg/Abtei): Gadertal and Val Marebbe (formerly in Val Luson and lower Val Badia), South Tyrol, by 9,229 inhabitants, 95% as their mother tongue. Mareo/Enneberg/Marebbe are three names for the Mareo version which is spoken in the lower valley. Badiot is spoken in the upper valley.
The language varies from town to town. Less Germanized than Gherdëina, probably the closest to a pure Ladin. Spoken in Bolzano, extremely protected. Maréo/Badiot is said to be “completely different” from Fascian, Anpezan and Cadore. Part of South Tyrolean Ladin. Intelligible with Gherdëina. Not intelligible with Fodom.
Fodom, Alta Val Cordevole, Buchenstein or Livinallese Ladin: spoken in the municipalities of Livinallongo Col di Lana, Colle Saint Lucia and Arabba in the villages of Cherz, Alfauro and Varda in Belluno by about 80 to 90% of the population as their mother tongue. Fodom has two very different dialects, one in the main valley, Livinallongo Col di Lana Ladin, resembling Val Badia and the other, Colle Saint Lucia Ladin, looking more Italian. Heavy Venetian and Italian influence. Considered part of Dolomitic Ladin. Not intelligible with Val Badia. Similar to Agordo Ladin Venetian.
Intelligibility with Anpezan is not known. Intelligibility with Rocchesano Ladin is unknown but may be good.
Eastern Ladin (transitional to Alpine Venetian-Friulian)
Near Belluno in Belluno Province.
In practice, Eastern Ladin except Anpezan is regarded as a separate language from Dolomitic Ladin.
Eastern Ladin – differences.
Anpezan, Ampezzo or Ampezzano Ladin: Cortina d’Ampezzo, Belluno. Similar to Cadore Ladin. Spoken in the Ampezzo Valley of the Dolomites. Heavy Venetian influence, but has many archaic qualities since it was under Austrian rule for 400 years – longer than the surrounding areas. Halfway between Ladin and Venetian. Anpezan is said to be “completely different” from Fascian, Maréo/Badiot, Gherdëina and Cadore.
Considered part of Dolomitic Ladin. Intelligibility with Fodom is not known, but Anpezan is not intelligible with Val Badia. Anpezan can understand Central Cadore, especially Oltrechiusano Ladin. Oltrechiusano and Anpezan form a sort of a grouping.
Central Cadore Ladin (Cadorino): Spoken in Valle di Cadore, Pieve di Cadore, Perarolo di Cadore, Calalzo di Cadore and Domegge di Cadore, except Comelico and Sappada, with Venetian influences. It is spoken in the Cadore all the way down to Perarolo di Cadore. Below Perarolo, it turns into Venetian. It is not uniform and differs greatly across the area. Pozzale Ladin is very archaic, with Oltrechiusano traits. Calalzo Ladin and Domegge Ladin are also archaic.
Pieve di Cadore Ladin, Tai di Cadore Ladin, Sottocastello Ladin, Valle di Cadore Ladin, Calalzo di Cadore Ladin, Domegge di Cadore Ladin, Ospitale di Cadore Ladin and Perarolo di Cadore Ladin have few speakers left. In these places, a variety of Cadore Venetian is now spoken. Sometimes included in Ladin and sometimes not.
Eastern Cadore Ladin (Cadorino): Spoken in Lozzo di Cadore, Vigo di Cadore, Lorenzago di Cadore and Auronzo di Cadore. More conservative than Central Cadore. The Laggio Ladin of Vigo and Auronzo is very archaic, similar to Comelico. This is apparently a separate language from Central Cadore.
Aurunzo di Cadore speaks Aurunzo Ladin, an Eastern Cadore dialect. Also spoken in Rizzio. The dialect of Aurunzo is very archaic, similar to Comelico. Aurunzo is very similar to Oltrepiavano, but it is very different from Comelicese. Oltrepiavano/Aurunzo di Cadore may be a single language.
Comelico, Comelicese or Comeliano Ladin: widespread in Comelico, Belluno. It is the most conservative of the Eastern Cadore dialects, even more conservative than Anpezan. Similar to Cadore but could also be confused with Friulian. The Comelico dialect could be divided into two sections: 1) Eastern Comelico: towns of Costalissoio, Campolongo, San Pietro di Cadore, Mare, Presenzio and Cosalta di Cadore; 2) Western Comelico: towns of Candide, Casamazzagno, Dosoledo, San Nicolò, Cosat, Parola, Danta, Santo Stefano, Campitello and Casta.
Friulian
Friulian may be up to five separate languages instead of one.
The tiny towns of Erto e Casso (dialects Ertano and Cassanese), Claut and Cimolais in Friuli Venezeia Giulia speak a Rhaeto-Romansch dialect that is transitional between Friulian and Ladin. Later it came under Venetian influence. Ladin was formerly spoken in a nearby area, which explains the Ladin influence.
The people say they speak Friulian, but the towns voted not to be included in the Friulian speaking region. The variety is not intelligible with the rest of Friulian. It is probably not intelligible with Ladin either. The name is Vajontino. The nearby village of Casso speaks some sort of Venetian, possibly Ladino Venetian. It is not really known what this lect is, whether it it is Friulian or Ladin at its base. It is probably a Friulian lect that came under serious Cadore Ladin influence.
In the town of Forni di Sotto on the border between the Comelico Ladin and the Friulian region, a dialect called Fornese is spoken that is often considered to be a part of Ladin. However, it is a cross between Carnico or Carnian Friulian and Cadore Ladin, especially Comelicano. It is said to be so different from the rest of Carnico that it is not even a part of that language. At the same time, it does not seem to be Ladin either.
Probably similar to Vajontino, but intelligibility between this lect and Vajontino is not known. Probably not intelligible with Cadore Ladin. This is basically a Friulian dialect that has undergone profound Cadore Ladin influence.
The Central Friulian of Gemona di Friuli in the north of the province has difficult intelligibility with Northern Friulian dialects spoken in Moggia Ugidense only 10-15 miles away.
In addition, Low Friulian has a hard time understanding Carnian Friulian in the far north.
Karaim
Karaim is two separate languages instead of one, Halich Karaim and Trakai Karaim.
Crimean Tatar
Crimean Tatar is two separate languages instead of one, Crimean Tatar and Turkish Crimean Tatar.
Gaguaz
Maritime Gaguaz and Balkan Gaguaz are two separate languages instead of one – see Ethnologue.
Basque
Basque is actually four separate languages instead of one- Standard Basque, Souletin, Vizcayan, and Gipuzcoan.
There is a unified Basque that everyone speaks so that they can understand each other.
However, there are cases where Guipuzcoan cannot understand Viscayan.
Souletin and Biscayan (France) do not understand each other.
Zuberoan or Souletin is spoken in France. It is not intelligible with the other Basque dialects. Souletin has influence from Béarnese, a dialect of Gascon (Occitan).
Yiddish
Yiddish is two separate languages instead of one, Western Yiddish and Eastern Yiddish.
Ladino
I am not sure Ladino is a separate language as it appears to be intelligible with Spanish.
Channel Islands French
This is actually four languages instead of one, Jerriais, Serquiais, North Guernesiais and South Guernesiais.
Jèrriais or Jersey French is a French language spoken on Jersey Island. Jèrriais has some intelligibility of Guernésiais. There are 2,874 speakers left. 15% of the population understands the language. The language is being revived. It is recognized as a regional language by the British government. Monolingual children were showing up at school as late as 30 years ago. There is a heavy English and some Breton influence.
Serquiais is a separate language spoken on Sark, descended from the Jèrriais of the colonists of the 1500’s. The remaining speakers are mostly elderly. It has suffered in recent years due to the influx of tax exiles. It is not inherently intelligible to Jèrriais or Guernésiais, nor with the Norman spoken on coast. There are only 20 speakers left. Serquiais is the most different of all compared to Standard French.
Guernésiais is spoken in Guernsey. It is recognized by the British government as a regional language. Guernésiais and Jèrriais have some intelligibility. There are 1,327 speakers. Speakers are mostly over age 64. 14% of the population have some understanding of the language. No intelligibility of Serquiais.
There are two Guernésiais languages, North Guernésiais, spoken in the lower parishes, and South Guernésiais, spoken in the upper parishes. There is poor intelligibility between them. Only one variety is being revived. Most Guernsey residents use some Guernésiais words in everyday speech without even knowing it. Speakers were evacuated to the mainland during WW2, and they quit speaking the language.
Arbëreshë Albanian
Arbëreshë Albanian is actually five separate languages instead of one, Sicilian Albanian, Calabrian Albanian, Central Mountain Albanian, Campo Marino Albanian and Molise Albanian.
Arbëreshë Albanian spoken in Italy is actually five separate languages, Sicilian Albanian, Calabrian Albanian, Central Mountain Albanian, Campo Marino Albanian and Molise Albanian. From a migration in the 1400’s-1500’s. Not intelligible with Standard Albanian. 80,000 speakers. Taught in some schools.
Arvanitika Albanian
Arvanitika Albanian is actually three separate languages instead of one.
Arvanitika Albanian is spoken in Greece. Thracean Arvanitika, Northwestern Arvanitika, South Central Arvanitika, dialects of Arvanitika, are actually separate languages. 50,000 speakers.
Greek
Greek is made up of at least seven different languages instead of one – Standard Greek, Cappodachian Greek, Cypriot Greek, Cretan Greek, Pontic Greek, Olympos Greek and Mariupolitan Greek.
Cappadocian Greek is not extinct at all as was previously thought. Thought extinct in the 1960’s, it was rediscovered in 2005.
Cypriot Greek and Cretan have marginal intelligibility with Standard Greek. Cretan has ~80% intelligibility and Cypriot ~60% with Standard Greek. Mariupolitan Greek is probably a dialect of Pontic Greek. See The Story of Pu: The Grammaticalization in Space and Time of a Modern Greek Complementizer by Nick Nicholas.
The dialect of Olympos, a village on the Greek island of Karpathos, is not even intelligible to other residents of the island.
Mariupolitan Greek is spoken in Mariupol in the Ukraine. This is a group of Greeks who moved into the area 200 years ago. Their Greek lect is still spoken to this day. It has a great deal of Turkic in it from Crimean Tatar so it is hard for Greeks to understand.
Turkmen
Turkmen and Trukhmen are two separate languages.
