Noticeably happy and optimistic. / Bright and pleasant.

The state of being cheerful; joy.

plural of cheerfulness

(uncountable) A cheerful attitude; happiness; a good, happy, or positive mood.

(transitive) To gladden; to make cheerful; often with up. / (transitive) To infuse life, courage, animation, or hope, into; to inspirit; to solace or comfort.

(chiefly Canada, US) Cheerleading, especially when practiced as a competitive sport.

Third-person singular simple present indicative form of cheer

To say "cheers" as a toast.

plural of cheer

A common toast used when drinking in company. / (chiefly Britain, Australia, New Zealand, Canada, South Africa, informal) goodbye, especially as a sign-off in an email or after writing a comment.