n. 1.general term for any insect or similar creeping or crawling invertebrate 2.a fault or defect in a system or machine 3.a small hidden microphone 4.insects with sucking mouthparts and forewings thickened and leathery at the base 5.a minute life form (especially a disease-causing bacterium) bug v. 1.annoy persistently 2.tap a telephone or telegraph wire to get information