[ flahy ]
/ flaɪ /
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See synonyms for: fly / flew / flies / flown on Thesaurus.com

noun, plural flies.
Also called true fly . any of numerous two-winged insects of the order Diptera, especially of the family Muscidae, as the common housefly.
any of various winged insects, as the mayfly or firefly.
Angling. a fishhook dressed with hair, feathers, silk, tinsel, etc., so as to resemble an insect or small fish, for use as a lure or bait.
Fly, Astronomy. the constellation Musca.
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Question 1 of 7
Fill in the blank: I can’t figure out _____ gave me this gift.

Idioms about fly

    fly in the ointment, a detrimental factor; detraction: If there's one fly in the ointment, it's that there may not be the money to finish the job.

Origin of fly

First recorded before 950; Middle English flīe, Old English flēoge, flȳge; cognate with Middle Dutch vliege (Dutch vlieg ), Old High German flioga (German Fliege ); akin to fly2


flyless, adjective

Other definitions for fly (2 of 3)

Origin of fly

First recorded before 900; Middle English flīen, Old English flēogan; cognate with Old High German fliogan, German fliegen, Old Norse fljuga

synonym study for fly

1. Fly, flit, flutter, hover, soar refer to moving through the air as on wings. Fly is the general term: Birds fly. Airplanes fly. To flit is to make short rapid flights from place to place: A bird flits from tree to tree. To flutter is to agitate the wings tremulously, either without flying or in flying only short distances: A young bird flutters out of a nest and in again. To hover is to linger in the air, or to move over or about something within a narrow area or space: hovering clouds; a hummingbird hovering over a blossom. To soar is to (start to) fly upward to a great height usually with little advance in any other direction, or else to (continue to) fly at a lofty height without visible movement of the wings: Above our heads an eagle was soaring.


Other definitions for fly (3 of 3)

[ flahy ]
/ flaɪ /

adjective, fly·er, fly·est.
Slang. stylish, attractive, sophisticated, etc.: She put on silver stilettos, her flyest outfit, and plenty of bling, ready to party till dawn.
British Slang. aware and worldly; clever; smart: Adults generally found him sly and conniving, but his teenage followers were convinced he was fly.
British Slang. dexterous; agile; nimble.

Origin of fly

First recorded in 1805–15; perhaps special use of fly2
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What is a basic definition of fly?

Fly means to move through the air using wings or to be carried by the air. Fly also means to travel in a vehicle that can move through the air. As a noun, fly refers to several two-winged insects. Fly has many other senses as a verb and a noun.

Many birds and insects with wings are able to move through the air—that is, to fly. The wind or air currents can also make some items fly around without control, such as pieces of paper. The wind or other force blows these items around.

  • Real-life examples: Birds, bats, and insects are all able to fly. Paper, confetti, plastic bags, and baseballs often fly through the air when a wind blows.
  • Used in a sentence: Canada geese fly often south in the winter, resting in the same areas each year. 

Humans can’t fly—not without help, at least. We can fly in airplanes, helicopters, and hot air balloons that fly through the air using air currents to travel.

  • Used in a sentence: The airplane flew across the ocean.

As a noun, fly is used generally to refer to small winged insects. The insects in question usually belong to the Muscidae family, such as the housefly.

  • Real-life examples: Flies are incredibly common and you have probably been annoyed by them during your life. Food and smelly garbage attracts flies. Spiders hunt and eat flies by trapping them in webs.
  • Used in a sentence: He couldn’t concentrate on his work because of an irritating fly that kept landing on his head. 

Where does fly come from?

The first records of the verb fly come from before the 900s. It ultimately comes from the Old English verb flēogan. The noun fly is almost as old. The first records come from before 950. It ultimately comes from the Old English flēoge.

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What are some other forms related to fly?

  • flyable (adjective)
  • flyability (noun)
  • nonflyable (adjective)
  • reflyable (adjective)
  • flyless (adjective)

What are some synonyms for fly?

What are some words that share a root or word element with fly

What are some words that often get used in discussing fly?

How is fly used in real life?

Fly is a very common word that most often refers to moving through the air.

Try using fly!

Is fly used correctly in the following sentence?

A caterpillar spends its life on the ground until it turns into a butterfly and uses its wings to fly through the air.

How to use fly in a sentence

British Dictionary definitions for fly (1 of 3)

/ (flaɪ) /

verb flies, flying, flew or flown
noun plural flies

Derived forms of fly

flyable, adjective

Word Origin for fly

Old English flēogan; related to Old Frisian fliāga, Old High German fliogan, Old Norse fljūga

British Dictionary definitions for fly (2 of 3)

/ (flaɪ) /

noun plural flies

Derived forms of fly

flyless, adjective

Word Origin for fly

Old English flēoge; related to Old Norse fluga Old High German flioga; see fly 1

British Dictionary definitions for fly (3 of 3)

/ (flaɪ) /

adjective flyer or flyest slang
mainly British knowing and sharp; smart
mainly Scot furtive or sneaky
on the fly mainly Scot in secret; sneakily

Word Origin for fly

C19: of uncertain origin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for fly

[ flī ]

Any of numerous insects of the order Diptera, having one pair of wings and large compound eyes. Flies include the houseflies, horseflies, and mosquitoes. See more at dipteran.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.