The Collaborative International Dictionary of English v.0.48:

Thrips \Thrips\, n. [L., a woodworm, Gr. ?.] (Zool.)
   Any one of numerous small species of Thysanoptera, especially
   those which attack useful plants, as the grain thrips
   (Thrips cerealium).
   [1913 Webster]

   Note: The term is also popularly applied to various other
         small injurious insects.
         [1913 Webster]

WordNet (r) 3.0 (2006):

thrips
    n 1: any of various small to minute sucking insects with narrow
         feathery wings if any; they feed on plant sap and many are
         destructive [syn: thrips, thrip, thripid]