Transient

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.

Hasty; momentary; imperfect; brief; as, a transient view of a landscape.

Staying for a short time; not regular or permanent; as, a transient guest; transient boarders.

That which remains but for a brief time.

(physics) a short-lived oscillation in a system caused by a sudden change of voltage or current or load