'lighten up' definitions:

Make more cheerful; "the conversation lightened me up a bit" [syn: lighten, lighten up, buoy up] [ant: weigh down, weigh on]

Become more cheerful; "after a glass of wine, he lightened up a bit" [syn: lighten, lighten up, buoy up]

Make lighter or brighter; "The paint will brighten the room" [syn: brighten, lighten up, lighten] [ant: darken]

Become lighter; "The room lightened up" [syn: lighten, lighten up] [ant: darken]