verb (used with or without object)
- to become or make bright or brighter.
- to make or become bright or brighter
- to make or become cheerful
Old English *beorhtnian “to make bright” (see (adj.) + (1)). Intransitive sense, “to become brighter,” attested from c.1300. Figurative use from 1590s. Related: Brightened; brightening.