Source : Webster's Revised Unabridged Dictionary (1913)

Gypsy \Gyp"sy\, or Gipsy moth \Gip"sy, moth\ .
   A tussock moth (Ocneria dispar) native of the Old World, but
   accidentally introduced into eastern Massachusetts about
   1869, where its caterpillars have done great damage to fruit,
   shade, and forest trees of many kinds. The male gypsy moth is
   yellowish brown, the female white, and larger than the male.
   In both sexes the wings are marked by dark lines and a dark
   lunule. The caterpillars, when full-grown, have a grayish
   mottled appearance, with blue tubercles on the anterior and
   red tubercles on the posterior part of the body, all giving
   rise to long yellow and black hairs. They usually pupate in
   July and the moth appears in August. The eggs are laid on
   tree trunks, rocks, etc., and hatch in the spring.

Source : WordNet®

gipsy moth
     n : European moth introduced into North America; a serious pest
         of shade trees [syn: {gypsy moth}, {Lymantria dispar}]