[1] : The Collaborative International Dictionary of English v.0.48

celtic \celt"ic\ se^lt"i^k; ke^lt"i^k, a. l.
   celticus, gr. keltiko`s. see celt.
   of or pertaining to the celts; as, celtic people, tribes,
   literature, tongue. written also keltic.
   1913 webster
see also:
celt keltic 

[2] : The Collaborative International Dictionary of English v.0.48

celtic \celt"ic\, n.
   the language of the celts.
   1913 webster

   note: the remains of the old celtic language are found in the
         gaelic, the erse or irish; the manx, and the welsh and
         its cognate dialects cornish and bas breton.
         1913 webster

[3] : WordNet (r) 2.0

celtic
     adj : relating to or characteristic of the celts syn: gaelic
     n : a branch of the indo-european languages that judging from
         inscriptions and place names was spread widely over
         europe in the pre-christian era syn: celtic language
see also:
gaelic celtic language 

Celtic >> C Words
Celtic, definition of term: Celtic
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Celtic Language >> C Words
Celtic Language, definition of term: Celtic Language
celtic+language_pag1.html

Celtic Cross >> C Words
Celtic Cross, definition of term: Celtic Cross
celtic+cross_pag1.html