The Collaborative International Dictionary of English v.0.48:

Hemiptera \He*mip"te*ra\, n. pl. [NL., fr. Gr. ? half + ? wing,
   fr. ? to fly.] (Zool.)
   An order of hexapod insects having a jointed proboscis,
   including four sharp stylets (mandibles and maxill[ae]), for
   piercing. In many of the species (Heteroptera) the front
   wings are partially coriaceous, and different from the
   others.
   [1913 Webster]

   Note: They are divided into the Heteroptera, including the
         squash bug, soldier bug, bedbug, etc.; the Homoptera,
         including the cicadas, cuckoo spits, plant lice, scale
         insects, etc.; the Thysanoptera, including the thrips,
         and, according to most recent writers, the Pediculina
         or true lice. Hemipteral

WordNet (r) 3.0 (2006):

Hemiptera
    n 1: plant bugs; bedbugs; some true bugs; also includes
         suborders Heteroptera (true bugs) and Homoptera (e.g.,
         aphids, plant lice and cicadas) [syn: Hemiptera, order
         Hemiptera]