Matter

Any substance that has mass and takes up space.

Aviation Maintenance Technician Handbook — General, p. G-6

Also defined in 1 more source

Something that has mass, takes up space, and exists as a solid, liquid, or gas.

Aviation Maintenance Technician Handbook — Powerplant, p. G-17

Taught in GEN-J Quick reference, GEN-C Concepts, AF-A Concepts, AF-B Concepts, AF-B Quick reference, AF-M Concepts and 12 more.