Nouns

(n)transientone who stays for only a short time“transient laborers”
(n)transient(physics) a short-lived oscillation in a system caused by a sudden change of voltage or current or load

Adjectives

(a)transeunt, transientof a mental act; causing effects outside the mind
(s)ephemeral, passing, short-lived, transient, transitory, fugaciouslasting a very short time“the ephemeral joys of childhood”, “a passing fancy”, “youth's transient beauty”, “love is transitory but it is eternal”, “fugacious blossoms”