From Longman Dictionary of Contemporary Englishcheer up phrasal verb1HAPPYto become less sad, or to make someone feel less sadCheer up! The worst is over.They cheered up when they saw us coming along.cheer somebody ↔ upHere’s a bit of news that will cheer you up.You both need cheering up, I think.2cheer something ↔ up to make a place look more attractiveI bought some posters to cheer the place up a bit. →cheer→ See Verb table
Examples from the Corpus
cheer 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 visitslocalhospitals to cheer upsick children.• You'd better get dressed and cheer up. The guests are coming any minute.