on the wing

late 12c., wenge, from Old Norse vængr "wing of a bird, aisle, etc." (cf. Danish and Swedish vinge "wing"), of unknown origin, perhaps from a Proto-Germanic *we-ingjaz and ultimately from PIE root *we- "blow" (cf. Old English wawan "to blow;" see wind (n.)). Replaced Old English feðra (plural) "wings" (see feather). The meaning "either of two divisions of a political party, army, etc." is first recorded c.1400; theatrical sense is from 1790.

Verbal phrase wing it (1885) is from theatrical slang sense of an actor learning his lines in the wings before going onstage, or else not learning them at all and being fed by a prompter in the wings. The verb to wing "shoot a bird in the wing" is from 1802. The slang sense of to earn (one's) wings is 1940s, from the wing-shaped badges awarded to air cadets on graduation. To be under (someone's) wing "protected by (someone)" is recorded from early 13c. Phrase on a wing and a prayer is title of a 1943 song about landing a damaged aircraft.