General English


  • noun a general term for a small insect with two wings, of the order Diptera. Some flies cause diseases of plants (the frit fly) and some harm animals (the gadfly).


  • verb to move through the air or to cause an aircraft to move through the air in a controlled manner


  • verb to transport men or objects by aircraft


  • adjective streetwise, fashionable. A vogue term in black street slang of the mid-1980s, later used by whites.

Origin & History of “fly”

Historically, ‘move through the air’ is something of a secondary semantic development for fly. Its distant Indo-European ancestor, *pleu-, denoted rapid motion in general, and in particular ‘flowing’ or ‘floating’, and it produced such offspring as Greek pléo ‘sail, float’ and Sanskrit plu- ‘sail, swim’, as well as English fleet, flood, flow, fowl, plover, and pluvial. An extension to that base, *pleuk-, gave rise to Lithuanian plaukti ‘float, sail, swim’, and to prehistoric west and north Germanic *fleugan, source of German fliegen, Dutch vliegen, Swedish flyga, and English fly, all meaning ‘move with wings’. The insect-name fly is also of considerable antiquity, going back to a prehistoric Germanic derivative *fleugōn or *fleugjōn, but the origins of the adjective fly ‘crafty, sharp’ (19th c.) are not known.