sadden (v.)youdaoicibaDictYouDict[sadden 词源字典]
"to make sorrowful," 1620s, from sad + -en (1). Earlier verb was simply sade, from Old English sadian, which also could be the immediate source of the modern verb. Intransitive meaning "to become sad" is from 1718. Related: Saddened; saddening.[sadden etymology, sadden origin, 英语词源]