bug

noun

1.
general term for any insect or similar creeping or crawling invertebrate
Derived from:
buggy
2.
a fault or defect in a computer program, system, or machine
3.
a small hidden microphone; for listening secretly
Derived from:
bug
4.
insects with sucking mouthparts and forewings thickened and leathery at the base; usually show incomplete metamorphosis
5.
a minute life form (especially a disease-causing bacterium); the term is not in technical use