|Origin:||signale, from Medieval Latin, from Late Latin signalis 'of a sign', from Latin signum; SIGN1|
sig‧nal1 S3 W2 [countable]
a sound or action that you make in order to give information to someone or tell them to do something ➔ smoke signal
signal (for somebody) to do something
When she got up from the table, it was obviously the signal for us to leave.
The headmaster gave the signal to begin.
At a pre-arranged signal the lights went out.
an event or action that shows what someone feels, what exists, or what is likely to happen
These results are a signal that the child may need special help.
The display flashed a red warning signal.
A red flag is often used as a danger signal.
send/give a signal
This will send the wrong signal to potential investors.
a series of light waves, sound waves etc that carry an image, sound, or message, for example in radio or television
send (out)/transmit/emit a signal (to somebody)
This new pay-TV channel sends signals via satellite to cable companies.
In the 1970s it was illegal to transmit fax signals via the public telephone system.
receive/pick up/detect a signal
a small antenna which receives radio signals
The Coast Guard picked up a distress signal from a freighter 50 miles out at sea.
a piece of equipment with coloured lights, used on a railway to tell train drivers whether they can continue or must stop:
a stop signal
a signal failure (=when these lights do not work)