Bedeutung von “signal” — Learner’s Dictionary

signal

noun [ C ] us uk /ˈsɪɡnəl/
That light is a signal that the studio is being used.The flare was a signal that the ship was in trouble.Dogs can learn to respond to even the slightest signals.Her body language was sending out mixed signals.The flags can be used as signals to other ships.
ACTION

B2 a movement, light, or sound that gives information, or tells people what to do:

At a signal from their teacher, the children all held up their flags.
Don't move until I give / the signal.
WAVE

B2 a series of electrical waves that are sent to a radio, television, or mobile phone

PROOF

something that shows that something else exists or is likely to happen:

The changing colour of the leaves on the trees is a signal that it will soon be autumn.
TRAINS

a piece of equipment that tells trains to stop or to continue

VEHICLES/PEOPLE US

a piece of equipment that shows people or vehicles when to stop, go, or move carefully:

a traffic signal

(Definition von “signal noun” aus dem Cambridge Learner's Dictionary © Cambridge University Press)