unfruitful (adj.)youdaoicibaDictYouDict[unfruitful 词源字典]
late 14c., "barren," from un- (1) "not" + fruitful. Originally literal; figurative sense is attested from c. 1400. Related: Unfruitfully; unfruitfulness.[unfruitful etymology, unfruitful origin, 英语词源]