What is the meaning of bug?

noun

• General term for any insect or similar creeping or crawling invertebrate.
• A fault or defect in a computer program, system, or machine.
  • synonyms: glitch
• A small hidden microphone; for listening secretly.
• Insects with sucking mouthparts and forewings thickened and leathery at the base; usually show incomplete metamorphosis.
  • synonyms: hemipterous insect, hemipteran, hemipteron
• A minute life form (especially a disease-causing bacterium); the term is not in technical use.
  • synonyms: microbe, germ

verb

• Annoy persistently.
  • usage: "The children teased the boy because of his stammer"
  • synonyms: tease, badger, pester, beleaguer
• Tap a telephone or telegraph wire to get information.
  • usage: "The FBI was tapping the phone line of the suspected spy"; "Is this hotel room bugged"
  • synonyms: wiretap, tap, intercept