The Collaborative International Dictionary of English v.0.48:

Etacism \E"ta*cism\, n. [Gr. ? the letter ?, ?. Cf. Itacism.]
   (Greek Gram.)
   The pronunciation of the Greek [eta] (eta) like the Italian e
   long, that is like a in the English word ate. See Itacism.
   [1913 Webster]