Lighten up means to become less serious, more cheerful or more relaxed.
Lighten up! (informal) is an expression used to tell someone to be less serious or more cheerful.
Examples of use:
1. You’ve finished work for the day so maybe you should lighten up and enjoy your evening.
2. Will you lighten up! We’re tired of hearing you complain about everything today.
infinitive – lighten up
present simple – lighten up and lightens up
-ing form – lightening up
past simple – lightened up
past participle – lightened up
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