antepenult

noun

Etymology: Either formed from ante- + penult and modelled on Latin or a shortening of Latin antepaenultima/antepēnultima (syllaba).

1. The third-to-last syllable of a word.

   “This elementary instruction is language at its most advanced to minds trained on the accentuation of the antepenult (multiplicity) and on Sievers-type C2 half-line metrical patterns[.]”