What does fly mean?
Fly is one of English's most versatile words. As a verb, it describes movement through the air — birds and insects fly on wings, aircraft fly on lift generated by their engines, and people fly whenever they travel by plane. It also carries older senses: things can fly by in time ('time flies'), flee in haste, or be scattered by force. As a noun, a fly is a small two-winged insect of the order Diptera, most familiar as the household pest, though anglers also use artificial 'flies' as lures. In modern slang, fly doubles as an informal adjective meaning stylish or sharp, popularized by hip-hop culture. Even clothing borrows the word: the zippered or buttoned opening on a pair of trousers is called the fly. Few words span nature, technology, fashion, and everyday language so completely, making fly both a practical term and a richly layered piece of English vocabulary.
To move through the air using wings or aerodynamic lift; to travel in an aircraft; or, in an older sense, to flee or hurry away.
"The pilot will fly us from London to Edinburgh."
Intransitive use ('birds fly') is standard; the old sense of fleeing survives mainly in literary contexts.
A small winged insect of the order Diptera, especially the common housefly; also an artificial fishing lure made to resemble such an insect.
"A fly kept buzzing around the kitchen lamp."
(Informal) stylish, clever, or fashionable.
"He showed up in a fly leather jacket."
Slang, chiefly American, rooted in hip-hop culture.
The flap of cloth covering the fastening at the front of a pair of trousers.
"His shirt was untucked over his open fly."
Standard plural of the noun sense referring to the insect; 'flies' also refers collectively to multiple artificial fishing lures.
"Flies gathered around the picnic table within minutes."
"Time flies" — but the phrase may really trace back to a Latin pun: tempus fugit literally means 'time flees.'
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fly
Fly comes from the Old English verb flēogan, meaning to fly or soar, which traces back through Proto-Germanic roots shared with Old Norse fljúga and Old High German flugan. The noun sense — the insect — developed from the same Germanic word family, via Old English flēoge. Its closest relatives include the verbs flee and flow, all descending from related Indo-European roots concerned with rapid motion.
Related word forms
How fly is actually used
The verb 'fly' is highly versatile and appears in both literal and figurative uses; the adjective meaning 'stylish' is informal and chiefly associated with hip-hop and youth culture. The insect sense is usually written with a compound form (housefly, fruit fly) when precision matters.
Easily confused with fly
A flea is a wingless, jumping, bloodsucking insect, whereas a fly is typically a winged insect of the order Diptera.
'Flew' is the past-tense form of the verb 'fly', not the base form.