n 1 a  :  an insect or other creeping or crawling invertebrate animal (as a spider) - not used technically  b  :  any of various insects commonly considered esp. obnoxious: as (1) :  BEDBUG (2) :  COCKROACH (3) :  HEAD LOUSE  c  :  any of the order Hemiptera and esp. of its suborder Heteroptera of insects that have sucking mouthparts, forewings thickened at the base, and that lack a pupal stage between the immature stages and the adult - called also true bug   2 a  :  a disease-producing microorganism and esp. a germ  b  :  a disease caused by such microorganisms : esp  :  any of various respiratory conditions (as influenza or grippe) of virus origin .
 
 
 
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