permanence (n.)

"enduring, unchanging, unchanged, lasting or intended to last indefinitely," early 15c., from Old French permanent, parmanent (14c.) or directly from Latin permanentem (nominative permanens) "remaining," present participle of permanere "endure, hold out, continue, stay to the end," from per "through" (from PIE root *per- (1) "forward," hence "through") + manere "stay" (from PIE root *men- (3) "to remain").

Related: Permanently. As a noun meaning "permanent wave," by 1909. Of clothing, permanent press, in reference to a process designed to produce lasting creases in fabric," is attested from 1964.