Source : Webster's Revised Unabridged Dictionary (1913)

Choriambus \Cho`ri*am"bus\, n.; pl. L. {Choriambi}, E.
   {Choriambuses}. [L. choriambus, Gr. ?; ? a choreus + ?
   iambus.] (Anc. Pros.)
   A foot consisting of four syllables, of which the first and
   last are long, and the other short (- [crescent] [crescent]
   -); that is, a choreus, or trochee, and an iambus united.