mid-14c., from Old French ratifier (13c.), from Medieval Latin ratificare "confirm, approve," literally "fix by reckoning," from Latin ratus "fixed by calculation; determined; approved; certain, sure; valid" (past-participle adjective from reri "to reckon, think;" from PIE root *re- "to reason, count") + combining form of facere "to make" (from PIE root *dhe- "to set, put"). Related: Ratified; ratifying.