c.1600, from Latin transiens (accusative transientem) "passing over or away," present participle of transire "cross over, pass away," from trans- "across" (see trans-) + ire "to go" (see ion). The noun is first attested 1650s; specific sense of "transient guest or boarder" first recorded 1880.
1. A sudden, brief increase in current or voltage in a circuit that can damage sensitive components and instruments. (2003-06-12) 2. A software object with a short and limited lifetime which is not saved for later reuse. (1998-04-19)