英语词源字典 - 在线词源网站

fruitful (adj.)[fruitful 词源字典]: c. 1300, of trees, from fruit + -ful. Related: Fruitfully; fruitfulness. Of animals or persons from early 16c.; of immaterial things from 1530s.[fruitful etymology, fruitful origin, 英语词源]
unfruitful (adj.): late 14c., "barren," from un- (1) "not" + fruitful. Originally literal; figurative sense is attested from c. 1400. Related: Unfruitfully; unfruitfulness.