As a Noun: 1. The outer edge or boundary of an area or object. In geometry, the continuous line forming the boundary of a closed object. English = perimeter. Note: 1. This sign uses two P handshapes from the one-handed alphabet. It was originally borrowed from American Sign Language (ASL) for use in deaf education (mathematics and geometry) in Australia. It has become accepted and used by some Auslan signers, especially teachers of the deaf, their students, and interpreters.