Definition of fly noun from the Oxford Advanced Learner's Dictionary



    BrE BrE//flaɪ//
    ; NAmE NAmE//flaɪ//
    (pl. flies) Invertebrates
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  1. 1   [countable] a small flying insect with two wings. There are many different types of fly. A fly was buzzing against the window. Flies rose in thick black swarms. See related entries: Invertebrates
  2. in fishing
  3. 2[countable] a fly or something made to look like a fly, that is put on a hook and used as bait to catch fish fly fishing Wordfinderbait, bite, dragnet, fishing, fly, hook, line, net, rod, trawl
  4. on trousers/pants
  5. 3[singular] (British English also flies) an opening down the front of a pair of trousers/pants that fastens with a zip or buttons and is usually covered over by a strip of material Your fly is undone! Your flies are undone!
  6. on tent
  7. 4[countable] a piece of material that covers the entrance to a tent
  8. see also flies
    Word Originnoun senses 3 to 4 Old English flēogan, of Germanic origin; related to Dutch vliegen and German fliegen, also to fly, the insect. noun senses 1 to 2 Old English flȳge, flēoge, denoting any winged insect, of West Germanic origin; related to Dutch vlieg and German Fliege, also to fly (verb). Extra examplesA fly settled on the butter. Do you know your flies are undone? I swatted the fly with a newspaper.Idioms
    die/fall/drop like flies
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    (informal) to die or fall down in very large numbers People were dropping like flies in the intense heat.
    a/the fly in the ointment
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    a person or thing that spoils a situation or an occasion that is fine in all other ways
    a person who watches others without being noticed I'd love to be a fly on the wall when he tells her the news. fly-on-the-wall documentaries (= in which people are filmed going about their normal lives as if the camera were not there)
    (there are) no flies on somebody
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    (informal) the person mentioned is clever and not easily tricked
    to be kind and gentle and unwilling to cause unhappiness (informal) if you do something on the fly, you do it quickly while something else is happening, and without thinking about it very much
See the Oxford Advanced American Dictionary entry: fly