cheer_up
1. [ verb ] cause (somebody) to feel happier or more cheerful
Synonyms: jolly_along jolly_up cheer
Examples:

"She tried to cheer up the disappointed child when he failed to win the spelling bee"

Related terms: amuse cheerfulness cheer
2. [ verb ] become cheerful
Synonyms: chirk_up cheer
Related terms: complain rejoice exult lighten lighten cheerfulness