Epenthesis

·noun The insertion of a letter or a sound in the body of a word; as, the b in "nimble" from ·AS n/mol.

epenthesis
ĕpenthĕsis, is, f., = ἐπένθεσις, the insertion of a letter , Serv. ad Verg. G. 1, 164. ...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.