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Quendian: The common language of all the Quendi when Orome found them at Cuiviénen . There were doubtless different dialects of this speech in the three Elvish clans from the very beginning. "Quenderin" was a technical term later invented by Noldorin loremasters .
Valarin: The language of the Valar. The Valarin had an influence on all Quendian languages, especially Quenya, which borrowed a number of words from it. The Valar seem to have abandoned Valarin in favour of Quenya as time passed .
Common Eldarin: It is unclear wether or not Common Eldarin can be considered a clearly distinguishable language, or if it was just a convenient linguistic term, used when describing elements common in the Eldarin languages (similar to today's usage of "Common Germanic"). The fact that the Common Telerin diverged so early from the other Eldarin languages should indicate that the latter was true, but on the other hand there is known to have been repeated contact between the Teleri and the Noldor during the Great March, so some joint development from Quendian in the speeches of the two clans is conceivable.
Avarin Languages: The Avari slowly spread across Middle-earth and developed an unknown number of languages. Very little is known about these languages; one of their late representatives was the Silvan of the Vale of Anduin.
Common Telerin: Already when they set out on the Great March, the language of the Teleri was distinct from that of the Vanyar and Noldor, and this distinction was probably strengthened during the long westward march .
Nandorin: The collective name for the languages of the Nandor, those Teleri who broke off from the Great March when they came to the river Anduin, and settled in Rhovanion and Eriador . All the Nandorin languages seem to have died out in the course of the First Age, because there is no trace of them in later ages.
Quenya: The language of the Vanyar and Noldor in Aman, called "Quendya" in Vanyarin dialect . When the exiled Noldor came to Beleriand their language was slightly influenced by the Sindarin speech. This new dialect, referred to as "Exilic Quenya" , was not used for long in Beleriand, partially because of Thingol's ban. Instead the Noldor took on a dialect of Sindarin, enriched by their own language. The exiles kept Quenya as a language of lore and songs, and returned with it, in the Second Age, to Tol Eressea, where it was distinguished as "Eressean" .
Amanya Telerin: The speech of the Teleri who arrived in Aman. It is often referred to as being a dialect of Quenya, by which it undoubtedly became influenced, but historically this is clearly not true. Also called simply Telerin .
Sindarin: The language of the Sindar, the Teleri who stayed in Beleriand. At the beginning of the First Age, three major dialects had developed: the dialects of the Falathrim, the Mithrim and the Iathrim. None of the dialects were so disparate as to prevent intercourse .
When the exiled Noldor appeared, the Iathrim were forbidden by their king Thingol to speak in or answer to Quenya, and thus that dialect was kept free of the strong Quenya influences that affected the other dialects .
It is not known what happened to the Sindarin dialects in the Second Age. They might have been maintained by the emigrating Sindar, but no indication of this is given in the corpus. A new dialect appeared in Lothlórien, where the Silvan language of the Galadhrim merged with Sindarin . The Sindarin speech probably died out in the Fourth Age, but that is not known for certain. It may have been preserved by the Sindar who went to Aman after the end of the First Age.
The Laiquendi, or Green-elves, were Nandor who had slowly drifted westward and finally entered Beleriand in the beginning of the First Age. They became allies of the Iathrim , but being few and scattered they seem to have dwindled, and merged with the Sindar after the War of Wrath.
Silvan: The language of the Tawarwaith, the Woodland (Silvan) Elves of the Vale of Anduin. The two principal areas where Silvan was spoken were Lothlórien and northern Mirkwood, where it had probably been replaced by Sindarin by the end of the Third Age . Even though Silvan is once in the corpus stated to derive from the Nandorin tounge, by far the most evidence points at that Silvan is an Avarin language . A possible explanation to this mistake is that the Silvan had made the change from original Quendian kw to p, which was otherwise seen only in the Telerin languages .