From Longman Dictionary of Contemporary Englishcheer up phrasal verb1 HAPPYto become less sad, or to make someone feel less sad Cheer up! The worst is over. They cheered up when they saw us coming along.cheer somebody ↔ up Here’s a bit of news that will cheer you up. You both need cheering up, I think.2 cheer something ↔ up to make a place look more attractive I bought some posters to cheer the place up a bit. → cheer→ See Verb table
Examples from the Corpuscheer up• I tried to cheer him up by telling a joke.• Cheer up! It's not that bad.• Cheer up! It's not the end of the world.• Cheer up, Mandy - the insurance will cover most of the damage.• Cheer up, Phil! It's only a game, and you can't win every time.• Cheer up, Phil. You'll find another job.• As a clown he visits local hospitals to cheer up sick children.• You'd better get dressed and cheer up. The guests are coming any minute.