persistent (adj.)

"continue steadily and firmly in some state or course of action," especially in spite of opposition or remonstrance; "persevere obstinately," 1530s, from French persister (14c.), from Latin persistere "abide, continue steadfastly," from per "thoroughly" (from PIE root *per- (1) "forward," hence "through") + sistere "come to stand, cause to stand still" (from PIE *si-st-, reduplicated form of root *sta- "to stand, make or be firm"). Related: Persisted; persisting.

1540s, "steady or firm adherence to or continuance in a state, course of action, or pursuit that has been entered upon, especially if more or less obstinate," from French persistance, from persistant "lasting, enduring, permanent," from Latin persistentem (nominative persistens), present participle of persistere (see persist). In 16c. often spelled persistance, but the classical spelling prevailed. Meaning "continuance of an effect after the cause which gave rise to it is removed" is from 1862. Related: Persistency.