from
The Collaborative International Dictionary of English v.0.48
Red light \Red light\
1. an electrically operated set of lights at a road
intersection which has different lights visible to traffic
from different directions, designed to control vehicle
traffic through the intersection. Each set of lights
typically has a colored red light and also green and amber
lights; the color of the light which is lighted at any one
time changes automatically to control the flow of traffic
through the intersection, allowing flow from different
directions in alternating succession. Also called
{{traffic light}}, {traffic signal} or {{stop light}}.
When the red light is illuminated the signal means to
stop; green means to go; and amber means to stop or
procede through the intersection with caution. In simple
intersections of two roads, a red light visible to traffic
on one road will usually be accompanied by a green light
visible to traffic on the intersecting road. In some
locations the lights may be set to be illuminated in other
sequences or combinations; a blinking red light is
typically equivalent to a "stop" sign, and a blinking
amber light typically means "procede with caution".
[PJC]
2. the condition of a traffic light when the signal visible
to the driver of a vehicle is red, signalling that the
vehicle must stop and not enter the intersection; I got
seven red lights on the way to work.
[PJC]
3. figuratively, a sign or signal that one must stop doing
what one is presently doing; as, a fatal side effect is
often a red light to continuation of a clinical trial.
[PJC]