Tran·sient a.
 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.”
 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.


 transiently
      adv : for a very short time; "these three pions may actually be
            joined together transiently as a compound particle
            during the interchange process"