signal

1 /'sIgnFl/ noun (C)

1 a sound or action that you make in order to give information to someone or tell them to do something: signal (for sb) to do sth: A bell began to ring, the 8 o'clock signal to start work. | When he closes his book, it's a signal for everyone to stand up. | give a signal: Don't start yet - wait for me to give the signal. | at a signal (from sb): At a signal from their leader the worshippers knelt to pray. | danger signal/warning signal etc: A red flag is often used as a danger signal.

—see also: smoke signal

2 an event or action that shows what someone feels or what is likely to happen: signal that: Gorbachev's speech was a signal that major changes were on the way. | a clear signal: The opinion poll is a clear signal that voters do not support the President's foreign policy. | danger signal/warning signal: Rapid breathing is a danger signal and you should call your doctor. | send/give a signal: This will send the wrong signal to potential investors.

3 a series of light waves, sound waves etc that carry an image, sound, or message, such as is used in radio or television: send out/transmit a signal (to): The signal was sent out to our troops immediately. | receive/pick up a signal: Astronomers have been picking up faint signals that may be from a distant planet.

4 a piece of equipment with coloured lights, used on a railway to tell train drivers whether they can continue or must stop: signal failure (=when these lights do not work): The report confirmed that signal failure had been the cause of the accident.

2 verb signalled, signalling BrE, signaled, signaling AmE

1 (I, T) to give a signal in order to give information or tell someone to do something

(+ at): Mary was signalling wildly at us, but we didn't even notice. (+ to): The judge signaled to a police officer and the man was led away. (+ for): He pushed his plate away and signaled for coffee. | signal (to) sb to do sth: She was signalling to the children to stay outside.

2 (T) to make something clear by what you say or do: Both sides have signaled their willingness to start negotiations.

3 (T) to be a sign or proof of something: the lengthening days that signal the end of winter

3 adjective (only before noun) formal important: signal achievement/success/failure etc: Getting the health care bill passed was a signal personal triumph for the President.