sig‧nal 1 S2 W2 / sɪɡn ə l / 名词 [可数名词]
1 a sound or an action that you make in order to give information to someone or tell them to do something
signal (for somebody) to do something
When she got up from the table, it was obviously the signal for us to leave.
At a prearranged signal the lights went out. → smoke signal
2 an event or action that shows what someone feels, what exists, or what is likely to happen
signal (that)
These results are a signal that the child may need special help.
signal of
The opinion poll is a clear signal of people’s dissatisfaction with the government.
the danger signals of a heart attack
send/give out a signal
We don’t want to give out the wrong signal to investors.
3 a series of light waves, sound waves etc that carry an image, sound, or message, for example in radio or television
send/transmit a signal
This new pay-TV channel sends signals via satellite to cable companies.
receive/pick up/detect a signal
a small antenna which can receive radio signals
The coastguard picked up a distress signal from a freighter 50 miles out at sea.
4 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 )
→ busy signal at busy 1 ( 4 )
COLLOCATIONS
ADJECTIVES/NOUN + signal
a clear/strong signal My body was giving me a clear signal that something was wrong.
a warning/danger/alarm signal (= a signal showing that there is danger ) Managers should keep a watchful eye open for the danger signals.
the wrong signals (= ones that do not give a true account of a situation ) Reducing the penalty for marijuana use perhaps sends the wrong signal to teenagers.
mixed signals (= ones that are confusing because they seem to show two different things ) Our culture gives girls mixed messages about food, with skinny models and fast-food commercials competing for attention.
动词
send/give out a signal The use of the army sends out a clear signal to protesters that their actions will not be tolerated.
read the signals (= to understand signals correctly ) President Nixon read the signals and decided it was time to resign.
COLLOCATIONS
动词
send (out)/transmit a signal The signals are transmitted via satellites.
emit a signal (= sends one out ) The device emits a signal which can be picked up by a submarine.
receive/pick up a signal The antenna that will pick up the signals is a 12-metre dish.
carry a signal (= allow it to travel along or through something ) Copper wires carry the electrical signals.
a signal travels (= goes across space, along a wire etc ) The signal travels over the cable network.
ADJECTIVES/NOUN + signal
strong I can’t use my phone because the signal isn’t strong enough here.
weak/faint The signals were too weak for the receiver to pick up.
a radio/electrical/radar signal A transmitter connected to the door bell sends radio signals to a portable receiver.
a digital signal Digital signals can be compressed to take up less space.
THESAURUS
sign [可数名词] an event, fact etc that shows that something is happening or that something is true or exists : The curtains were still drawn and there was no sign of activity. | A score of 80 or more is a sign that you are doing very well.
indication [可数名词] a sign. Indication is more formal than sign : Recently there have been several indications of improving relations. | There was no indication the killings were related to the drug trade.
evidence [不可数名词] facts or signs that show clearly that something exists or is true, especially something that you are trying to prove : Scientists are hoping to find evidence that there was once life on Mars. | There was not enough evidence to convict him of the murder.
symptom [可数名词] a sign that someone has an illness or that a serious problem exists : The first symptoms are tiredness and loss of weight. | Is this a symptom of the decay of Western civilization?
indicator [可数名词] a sign that shows you what is happening or what is true – used about a process, or about the state or level of something : There are a number of indicators of economic slowdown. | The tests are considered a good indicator of intelligence.
signal [可数名词] a sign that shows that you should do something, or that you have a particular attitude : Severe chest pain is a warning signal that cannot be ignored. | Legalizing drugs could send the wrong signal to young people.
mark [可数名词] a sign, especially that you respect or honour someone : People stood in silence as a mark of respect. | It was a mark of her popularity that so many colleagues and friends attended the presentation.