The Collaborative International Dictionary of English v.0.48:

Trochee \Tro"chee\, n. [L. trochaeus, Gr. ? (sc.?), from ?
   running, from ? to run. Cf. Troche, Truck a wheel.]
   (Pros.)
   A foot of two syllables, the first long and the second short,
   as in the Latin word ante, or the first accented and the
   second unaccented, as in the English word motion; a choreus.
   [1913 Webster]

WordNet (r) 3.0 (2006):

trochee
    n 1: a metrical unit with stressed-unstressed syllables