Source : Webster's Revised Unabridged Dictionary (1913)

Bacchius \Bac*chi"us\, n.; pl. {Bacchii}. [L. Bacchius pes, Gr.
   ? (sc. ? foot).] (Pros.)
   A metrical foot composed of a short syllable and two long
   ones; according to some, two long and a short.

Source : WordNet®

bacchii
     See {bacchius}