A bug is an insect. You might refuse to go camping because of your intense dislike for bugs. Bug can also be a verb meaning "annoy." Most likely, bugs bug you.

There are bugs you can see, like bees, and bugs that are much smaller, like viruses and bacteria. If you get one of these microscopic bugs, it means you're sick. You can also say, casually, "I've caught the model train bug — I'm hooked!" A microphone that's hidden in someone's home or telephone is also a bug, named after its small size. To bug someone means either to spy on them, or simply to bother them relentlessly.

Definitions of bug
  1. noun
    general term for any insect or similar creeping or crawling invertebrate
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    type of:
    small air-breathing arthropod
  2. noun
    insects with sucking mouthparts and forewings thickened and leathery at the base; usually show incomplete metamorphosis
    synonyms: hemipteran, hemipteron, hemipterous insect
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    show 11 types...
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    leaf bug, plant bug
    small bright-colored insect that feeds on plant juices
    lygaeid, lygaeid bug
    a true bug: usually bright-colored; pest of cultivated crops and some fruit trees
    coreid, coreid bug
    a true bug
    Cimex lectularius, bed bug, bedbug, chinch
    bug of temperate regions that infests especially beds and feeds on human blood
    Notonecta undulata, backswimmer
    predaceous aquatic insect that swims on its back and may inflict painful bites
    true bug
    any of various insects of the order Hemiptera and especially of the suborder Heteroptera
    capsid, mirid, mirid bug
    a variety of leaf bug
    lace bug
    small bug having body and wings covered with a lacy network of raised lines
    Blissus leucopterus, chinch bug
    small black-and-white insect that feeds on cereal grasses
    Anasa tristis, squash bug
    large black American bug that sucks sap of vines of the gourd family
    leaf-foot bug, leaf-footed bug
    large sap-sucking bug with leaflike expansions on the legs
    type of:
    small air-breathing arthropod
  3. noun
    a minute life form (especially a disease-causing bacterium); the term is not in technical use
    synonyms: germ, microbe
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    type of:
    micro-organism, microorganism
    any organism of microscopic size
  4. verb
    annoy persistently
    synonyms: badger, beleaguer, pester, tease
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    type of:
    bedevil, crucify, dun, frustrate, rag, torment
    treat cruelly
  5. noun
    a small hidden microphone; for listening secretly
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    type of:
    microphone, mike
    device for converting sound waves into electrical energy
  6. verb
    tap a telephone or telegraph wire to get information
    “Is this hotel room bugged?”
    synonyms: intercept, tap, wiretap
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    type of:
    eavesdrop, listen in
    listen without the speaker's knowledge
  7. noun
    a fault or defect in a computer program, system, or machine
    synonyms: glitch
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    type of:
    defect, fault, flaw
    an imperfection in an object or machine
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