straight·edge 
(strātĕj′)
(strātĕj′)n.
A rigid flat rectangular bar, as of wood or metal, with a straight edge for testing or drawing straight lines.
adj. also straight-edge (strātĕj′)
1. Having a level, even edge: a straightedge ruler; a straightedge razor blade.
2. Abstaining from alcohol, tobacco, and drugs.
straightedged′ adj.