promising (adj.)

c. 1400, promisen, "make a promise of," from promise (n.). Meaning "afford reason to expect" is from 1590s. Related: Promised; promising. In Middle English also promit (promitten), from the Latin verb. The promised land (1530s, earlier lond of promission, mid-13c.; province of promissioun, late 15c.) is a reference to the land of Canaan promised to Abraham and his progeny (Hebrew xi:9, etc.; Greek ten ges tes epangelias).

1660s, from un- (1) "not" + promising (adj.).