1. n - In Carpentry, usually the thinnest side of a piece of lumber. eg. on a 1"x4" x 2'-0", the the edge is the 2'-0" long x 3/4" tall side. 2a. n - In lighting and Video, the outer most part of a light beam's throw. Fresnels=soft-edged lighting, ERSs=hard-edged. 2b. n - Some lighting desks use "edge" rather than "focus" when referring to the sharpness of a gobo, so as not to confuse with focus of pan & tilt. 3. The perimeter of anything.