The Collaborative International Dictionary of English v.0.48:

Keltic \Kelt"ic\ (k[e^]lt"[i^]k), a. & n.
   Same as Celtic, a. & n.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Celtic \Celt"ic\ (s[e^]lt"[i^]k; k[e^]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]