lighten up

Found in Anh - Anh (Wordnet)

Definition Verb (Phrasal Verb) : To become less serious, tense, or gloomy; to adopt a more cheerful or relaxed attitude : This is the primary idiomatic meaning. It is an instruction or observation about someone's mood or demeanor becoming more positive. To become brighter or less dark : This is the literal meaning, referring to a reduction in darkness or an increase in illumination. Usage and E...