A teaching assistant.

The action of playing imaginary drums, usually to accompany music that one is listening to.

A small amount of air in a pipe that stops liquid flowing through it.

A bearing in which a thin film of pressurized air is used to provide an exceedingly low-friction load-bearing interface between surfaces.

plural of air lock

A temporary facility, such as a tent, set up to provide supplies to participants in endurance events, or first aid and provisions during disasters, military operations, etc.

plural of aid station

(video games) Automatic adjustment to aim to improve accuracy.

An alveolus / An extension of a lung of some birds

(skiing, snowboarding) A discipline in freestyle skiing and snowboarding, involving sliding down a large launch ramp and then launching off a big kicker, to obtain height and time in the air to perform acrobatic maneuvers, and land on a landing slope.