1. [n]  (physics) a short-lived oscillation in a system caused by a sudden change of voltage or current or load
2. [n]  one who stays for only a short time; "transient laborers"
3. [adj]  (philosophy) of a mental act; causing effects outside the mind
4. [adj]  enduring a very short time; "the ephemeral joys of childhood"; "a passing fancy"; "youth's transient beauty"; "love is transitory but at is eternal"; "fugacious blossoms"

1. \Tran"sient\, a. [L. transiens, -entis, p. pr. of
   transire, transitum, to go or pass over. See {Trance}.]
   1. Passing before the sight or perception, or, as it were,
      moving over or across a space or scene viewed, and then
      disappearing; hence, of short duration; not permanent; not
      lasting or durable; not stationary; passing; fleeting;
      brief; transitory; as, transient pleasure. ``Measured this
      transient world.'' --Milton.
   2. Hasty; momentary; imperfect; brief; as, a transient view
      of a landscape.
   3. Staying for a short time; not regular or permanent; as, a
      transient guest; transient boarders. [Colloq. U. S.]
   Syn: {Transient}, {Transitory}, {Fleeting}.
   Usage: Transient represents a thing as brief at the best;
          transitory, as liable at any moment to pass away.
          Fleeting goes further, and represents it as in the act
          of taking its flight. Life is transient; its joys are
          transitory; its hours are fleeting.
                What is loose love? A transient gust. --Pope
                If [we love] transitory things, which soon
                decay, Age must be loveliest at the latest day.
                                                  --Donne.
                O fleeting joys Of Paradise, dear bought with
                lasting woes.                     --Milton.
          -- {Tran"sient*ly}, adv. -- {Tran"sient*ness}, n.
   

2. \Tran"sient\, n.
   That which remains but for a brief time. --Glanvill.
   

1. A sudden, brief increase in current or voltage in a circuit that can damage sensitive components and instruments.

2. A software object with a short and limited lifetime which is not saved for later reuse.