The noun cheer has 2 senses (first 1 from tagged texts)
1. (14) cheer -- (a cry or shout of approval)
2. cheerfulness, cheer, sunniness, sunshine -- (the quality of being cheerful and dispelling gloom; "flowers added a note of cheerfulness to the drab room")
Overview of verb cheer
The verb cheer has 5 senses (first 2 from tagged texts)
2. (1) cheer -- (show approval or good wishes by shouting; "everybody cheered the birthday boy")
3. cheer, cheer up, jolly along, jolly up -- (cause (somebody) to feel happier or more cheerful; "She tried to cheer up the disappointed child when he failed to win the spelling bee")
4. cheer, cheer up, chirk up -- (become cheerful)
5. cheer, inspire, urge, barrack, urge on, exhort, pep up -- (urge on or encourage especially by shouts; "The crowd cheered the demonstrating strikers")