\Troch"i*lus\, n.; pl. {Trochili}. [L. trochilus a
kind of small bird. Gr. ?, fr. ? to run.]
1. (Zo["o]l.)
   (a) A genus of humming birds. It Formerly included all the
       known species.
   (b) Any one of several species of wrens and kinglets.
       [Obs.]
   (c) The crocodile bird.
2. (Arch.) An annular molding whose section is concave, like
   the edge of a pulley; -- called also {scotia}.