(idiomatic) A greeting, usually for birthdays, in reference to the passing year; Happy birthday!

(chiefly UK and Ireland, idiomatic, vulgar, simile) Extremely happy; obviously satisfied and carefree.

(dated) Angelman syndrome

plural of happy little vegemite

(Australia) A contented and well-behaved child; a very pleased person; often used ironically.

Alternative form of Happy New Year

A Native American idea of the afterlife, conceived of as a paradise in which hunting is plentiful and game unlimited.

plural of happy hunting ground

plural of happy ever after

(authorship) A happy ending; a good fate, life, or ending to a story.