The Collaborative International Dictionary of English v.0.48:

Snowcap \Snow"cap`\, n. (Zool.)
   A very small humming bird (Microchaera albocoronata) native
   of New Grenada.
   [1913 Webster]

   Note: The feathers of the top of the head are white and
         snining, the body blue black with a purple and bronzy
         luster. The name is applied also to Microchaera
         parvirostris of Central America, which is similar in
         color.
         [1913 Webster]

WordNet (r) 3.0 (2006):

snowcap
    n 1: a covering of snow (as on a mountain peak)