This article is from the Enya FAQ, by Kevin Martin enyafaq@brasscannon.org with numerous contributions by others.
Enya's non-English songs are generally sung in Irish, which is her first
language.
Irish belongs to the Goidelic, or Gaelic, branch of the Celtic family of
languages. This branch consists of Irish, (Scottish) Gaelic and Manx.
Irish speakers refer to their language as 'Gaeilge' (i.e. Gaelic), but the
English word 'Gaelic', unqualified, normally refers only to Scottish
Gaelic. So when using standard English to describe Enya's native tongue it
is correct to say either 'Irish' or 'Irish Gaelic.' (And by the way -
Celtic is pronounced "Keltic," NOT "Seltic".)
Of the other songs, four are sung in Latin (Cursum Perficio, Afer Ventus,
Pax Deorum, Tempus Vernum), one is in Welsh (Dan Y Dwr), and one in Spanish
(La Sonadora). Also, a few lines of French are sung in the mostly English
'Only If'.
With the release of the soundtrack for Lord of the Rings, we can add the
Elvish languages invented by J.R.R. Tolkien. "May It Be" has a passage in
Quenya. The other Elvish language, called Sindarin, is sung by Enya in the
song "Aniron" (which in Sindarin means "I Desire").
 
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