fly¹ / flī/ • v. (flies / flīz/ ; past flew / floō/ ; past part. flown / flōn/ ) [intr.] 1. (of a bird or other winged creature) move through the air under control: close the door or the moths will fly in the bird can fly enormous distances. ∎  (of an aircraft or its occupants) travel through the air: I fly back to New York this evening. ∎  [tr.] control the flight of (an aircraft); pilot. ∎  [tr.] transport in an aircraft: helicopters flew the injured to a hospital. ∎  [tr.] accomplish (a purpose) in an aircraft: pilots trained to fly combat missions. ∎  [tr.] release (a bird) to fly, esp. a hawk for hunting or a pigeon for racing.2. move or be hurled quickly through the air: balls kept flying over her hedge he was sent flying by the tackle. ∎  (past flied) Baseball hit a ball high into the air: Gwynn flied to left. ∎  (past flied) (fly out) Baseball (of a batter) be put out by hitting a fly ball that is caught. ∎  go or move quickly: she flew along the path. ∎ inf. depart hastily: I must fly! ∎  (of time) pass swiftly: how time flies! ∎  (of a report) be circulated among many people: rumors were flying around Chicago. ∎  (of accusations or insults) be exchanged swiftly and heatedly: the accusations flew thick and fast.3. (esp. of hair) wave or flutter in the wind: they were running, hair flying everywhere. ∎  (of a flag) be displayed, esp. on a flagpole: flags were flying at half-mast. ∎  [tr.] display (a flag).4. archaic flee; run away: those that fly may fight again. ∎  [tr.] flee from; escape from in haste: you must fly the country for a while.• n. (pl. flies) 1. an opening at the crotch of a pair of pants, closed with a zipper or buttons and typically covered with a flap. ∎  a flap of material covering the opening or fastening of a garment or of a tent: [as adj. in comb.] a fly-fronted shirt. 2. (the flies) the space over the stage in a theater.3. Baseball short for fly ball.4. (pl. usu. flys) Brit. & hist. a one-horse hackney carriage. PHRASES: fly the coop inf. make one's escape.fly the flagsee flag¹ .fly high be very successful; prosper: that young man is the sort to fly high.fly in the face of be openly at variance with (what is usual or expected): a need to fly in the face of convention.fly into a rage (or temper) become suddenly or violently angry.fly the nest (of a young bird) leave its nest on becoming able to fly. ∎ inf. (of a young person) leave their parents' home to set up home elsewhere.fly off the handle inf. lose one's temper suddenly and unexpectedly.go fly a kite [in imper.] inf. go away.on the fly while in motion or progress: his deep shot was caught on the fly. ∎  Comput. during the running of a computer program without interrupting the run.PHRASAL VERBS: fly at attack (someone) verbally or physically: Robbie flew at him, fists clenched. ∎  (of a hawk) pursue and attack, or habitually pursue (prey). ∎  (fly a hawk at) send a hawk to pursue and attack (prey).DERIVATIVES: fly·a·ble adj.fly² • n. (pl. flies / flīz/ ) a flying insect (order Diptera) of a large order characterized by a single pair of transparent wings and sucking (and often also piercing) mouthparts. Flies are noted as vectors of disease. ∎  [usu. in comb.] used in names of flying insects of other orders, e.g., butterfly, dragonfly, firefly. ∎  an infestation of flying insects on a plant or animal: cattle treated for warble fly. ∎  a natural or artificial flying insect used as bait in fishing, esp. a mayfly.PHRASES: die (or drop) like flies die or collapse in large numbers. a fly in the ointment a minor irritation that spoils the success or enjoyment of something.fly on the wall an unnoticed observer of a particular situation.fly³ • adj. (fly·er , fly·est) inf. 1. stylish and fashionable: they were wearin' fly clothes. 2. Brit. knowing and clever; worldly-wise: she's fly enough not to get done out of it.DERIVATIVES: fly·ness n.