A BIRO brand ballpoint pen. / (by extension, UK, Australia, New Zealand) Any ballpoint pen. / (uncountable, by extension) Ink from a ballpoint pen.

Voluntary control of the number of children conceived, especially by the planned use of contraception. / Any technique used to prevent the birth of a child (such as abortion or preventing conception).

A major city and metropolitan borough of the West Midlands, England, with a population of over one million. / A city, the county seat of Jefferson County, Alabama, United States.

A bird, such as a canary or budgerigar, kept captive in a cage or aviary for domestic companionship or as a hobby.

A tropical bird, Phaethon aethereus, often found far from land, whose cry resembles the whistle of a boatswain's pipe.

(idiomatic) I received the information from a source not to be overtly exposed.

Avian influenza.

A birth in which the baby comes through the birth canal posterior (buttocks), feet, or knees first, instead of the more usual position of headfirst.

(colloquial, idiomatic) To make a rude or obscene gesture (at somebody); particularly, to extend the middle finger. / Used other than figuratively or idiomatically: see flip, bird.

Any bird of the Australasian family Ptilonorhynchidae noted for building display structures (bowers) and decorating them with bright objects such as shells, glass, flowers, etc.