The term 'Octagonal Traffic Sign' refers to a STOP sign, which is an eight-sided shape with the word 'STOP' written in white on a red background. STOP signs are used to indicate that vehicles must come to a complete STOP before proceeding. They are typically placed at intersections and other areas where traffic needs to be regulated. The octagonal shape of the sign is used to make it easily recognizable and distinguishable from other signs.