Incessant

google

ref

late Middle English: via Old French from late Latin incessant-, from in- ‘not’ + Latin cessant- ‘ceasing’ (from the verb cessare ).

wiktionary

ref

From Old French incessant

etymonline

ref

incessant (adj.)

mid-15c., from Old French *incessant or directly from Late Latin incessantem (nominative incessans) "unceasing," from Latin in- "not" (see in- (1)) + cessans, present participle of cessare "to cease, go slow, give over, leave off, be idle," frequentative of cedere (past participle cessus) "go away, withdraw, yield" (from PIE root *ked- "to go, yield"). Related: Incessantly (early 15c.).