1. Being full of or promoting cheer; having or showing good spirits
   "her cheerful nature"; "a cheerful greeting"; "a cheerful room"; "as cheerful as anyone confined to a hospital bed could be" 
2. Pleasantly (even unrealistically) optimistic
   - pollyannaish, upbeat

See also: beaming, beamish, blithe, blithesome [archaic], buoyant, cheer, cheerfulness, cheery, chipper, chirpy, debonair, debonaire, gay, glad, happy, jaunty, lighthearted, light-hearted, lightsome, optimistic, perky, smiley, smiling, sunniness, sunny, sunshine, sunshiny, twinkly

Antonym: depressing

• crudely
• crudeness
• crudity
• crudités
• cruel
• cruel and unusual punishment
• cruel plant
• cruelly
• cruelness
• cruelty
• cruet
• cruet-stand
• cruise
• cruise control
• cruise liner
• cruise missile
• cruise ship
• cruiser
• cruiserweight
• cruller
• crumb
• crumb cake
• crumble
• crumbliness
• crumbly