momentary

From Middle English momentare, from Late Latin mōmentārius (“of brief duration”), from mōmentum (“a short time, an instant”). By surface analysis, moment +‎ -ary.

momentary (comparative more momentary, superlative most momentary)

Lasting for only a moment.
Happening at every moment; perpetual.
Ephemeral or relatively short-lived.
- 1749, [John Cleland], “(Please specify the letter or volume)”, in Memoirs of a Woman of Pleasure [Fanny Hill], London: […] [Thomas Parker] for G. Fenton [i.e., Fenton and Ralph Griffiths] […], →OCLC:
  Yet oh! what an immense difference did I feel between this impression of a pleasure merely animal, and struck out of the collision of the sexes by a passive bodily effect, from that sweet fury, that rage of active delight which crowns the enjoyments of a mutual love-passion, where two hearts, tenderly and truly united, club to exalt the joy, and give it a spirit and soul that bids defiance to that end which mere momentary desires generally terminate in, when they die of a surfeit of satisfaction!
- 1907 January, Harold Bindloss, chapter 20, in The Dust of Conflict, 1st Canadian edition, Toronto, Ont.: McLeod & Allen, →OCLC:
  Tony's face expressed relief, and Nettie sat silent for a moment until the vicar said “It was a generous impulse, but it may have been a momentary one, […] .”

lasting for only a moment

perpetual — see perpetual

ephemeral or relatively short-lived

Armenian: վաղանցիկ (hy) (vaġancʻik)
Bulgarian: краткотраен (bg) (kratkotraen)
Esperanto: momenta
Finnish: hetkellinen (fi), lyhytaikainen (fi)
German: vorübergehend (de)
Hungarian: átmeneti (hu), tünékeny (hu), röpke (hu)
Maori: rangitahi
Romanian: momentan (ro), efemer (ro)
Russian: преходя́щий (ru) (prexodjáščij), кратковре́менный (ru) (kratkovrémennyj), сиюмину́тный (ru) (sijuminútnyj)
Scottish Gaelic: sealach
Serbo-Croatian: trenutan (sh)
Swedish: flyktig (sv), kortlivad (sv), dagsländelik, efemär (sv)