A spirit level.

A siren that makes a very loud alarm sound to warn the population of an upcoming air raid.

plural of AIDS baby

A baby born with an HIV infection.

plural of air-raid warden

A jacket with airtight cells, or cavities which can be filled with air, to make the wearer buoyant when swimming.

plural of air jacket

An extensive cascade of ionized particles formed by the entry of a cosmic ray into the atmosphere

(snowboarding) A trick in which the boarder reaches the trailing hand back between the legs and grabs the heel edge of the board between the feet.

Someone who works for a charitable organisation devoted to helping others, especially one who works internationally or in conflict zones.