Alternative form of mockingbird

(idiomatic, UK, dated) A secret pledge that one makes for another.

Alternative spelling of lovebird

(Canada) In an educational institution, a course which is regarded as particularly easy.

(US, slang, military) A member of the United States armed forces having the rank of full colonel, as distinct from a lieutenant colonel.

plural of bird watcher

Alternative spelling of birdlime

Any of several albatrosses, especially the black-footed albatross (Phoebastria nigripes) and the Laysan albatross, that dwell primarily on islands in the Pacific Ocean, often near naval bases.

Alternative form of yardbird

(simile) Having no ties; completely free.