straightedge
any of various tools, usually long bars or strips of wood or metal, having straight and true edges and used for drawing or cutting accurate straight lines
en-US/ˈstɹeɪtˌɛd͡ʒ/
en-GB/stɹeɪtɛd͡ʒ/
any of various tools, usually long bars or strips of wood or metal, having straight and true edges and used for drawing or cutting accurate straight lines