brighten (v.)youdaoicibaDictYouDict[brighten 词源字典]
Old English *beorhtnian "to make bright" (see bright (adj.) + -en (1)). Intransitive sense, "to become brighter," attested from c. 1300. Figurative use from 1590s. Related: Brightened; brightening.[brighten etymology, brighten origin, 英语词源]