Arabesque: One leg is down straight and the other leg is behind you almost at a ninety degree angle to your back.
Arch: A position in which the back is curved.
Aerial: A cartwheel without hands touching the ground or floor. Sometimes called a walkover.
Attack the Crowd: A technique used to whip the crowd up and get them involved in a cheer, dance or song.
Base: The bottom person/persons in a stunt who remains on the ground while lifting a flyer into a stunt.