The Collaborative International Dictionary of English v.0.48:

Celt \Celt\, n. [LL. celts a chisel.] (Arch[ae]ol.)
   A weapon or implement of stone or metal, found in the tumuli,
   or barrows, of the early Celtic nations.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Celt \Celt\ (s[e^]lt; k[e^]lt), n. [L. Celtae, Gr. Keltoi`,
   Ke`ltai, pl.: cf. W. Celtiad one that dwells in a covert, an
   inhabitant of the wood, a Celt, fr. celt covert, shelter,
   celu to hide.]
   One of an ancient race of people, who formerly inhabited a
   great part of Central and Western Europe, and whose
   descendants at the present day occupy Ireland, Wales, the
   Highlands of Scotland, and the northern shores of France.
   [Written also Kelt. The letter C was pronounced hard in
   Celtic languages.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

Celt
    n 1: a member of a European people who once occupied Britain and
         Spain and Gaul prior to Roman times [syn: Celt, Kelt]