Transient

1. noun

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

2. adjective

   of a mental act; causing effects outside the mind

   Similar: transeunt

3. noun

   one who stays for only a short time

   “transient laborers”

4. adjective

   lasting a very short time

   “the ephemeral joys of childhood”

   Similar: ephemeral, passing, transitory, fugacious