The Collaborative International Dictionary of English v.0.48:

Corvet \Cor"vet\ (k?r"v?t), Corvette \Cor*vette"\ (k?r-v?r"), n.
   [F. corvette, fr. Pg. corveta or Sp. corbeta, fr. L. corbita
   a slow-sailing ship of burden, fr, corbis basket. Cf.
   Corbeil.] (Naut.)
   A war vessel, ranking next below a frigate, and having
   usually only one tier of guns; -- called in the United States
   navy a sloop of war.
   [1913 Webster]

WordNet (r) 3.0 (2006):

corvette
    n 1: a highly maneuverable escort warship; smaller than a
         destroyer