traffic light

Short definition from Wiktionary

Noun

1. 1
   A signalling device positioned at a road intersection or pedestrian crossing indicating the moment it is safe to drive, ride or walk, using a universal color code.
2. 2
   A signalling device positioned at a road intersection or pedestrian crossing indicating the moment it is safe to drive, ride or walk, using a universal color code: A road intersection controlled by one or more such devices.
3. 3
   A colour code using the three signals of a traffic light (green, yellow or amber, and red) as a metaphor.
4. 4
   The colored dots on stamp sheet margins printed with offset printing or photogravure methods, used by the printers to check color accuracy.
5. 5
   In Conway's Game of Life, an arrangement of four blinkers that are orthogonally equidistant from a central point.
6. 6
   Alternative spelling of traffic light.