The Collaborative International Dictionary of English v.0.48:

Epenthetic \Ep`en*thet"ic\, a. [Gr. ?: cf. F.
   ['e]penth['e]tique.] (Gram.)
   Inserted in the body of a word; as, an epenthetic letter or
   sound.
   [1913 Webster]

WordNet (r) 3.0 (2006):

epenthetic
    adj 1: of or pertaining to epenthesis [syn: epenthetic,
           parasitic]