signal

American  

[sig-nl] / ˈsɪg nl /

noun

1. anything that serves to indicate, warn, direct, command, or the like, such as a light, a gesture, an act, etc.: a signal to leave.

   a traffic signal;

   a signal to leave.

   Synonyms:

   sign

2. anything agreed upon or understood as the occasion for concerted action.

3. an act, event, or the like that causes or incites some action.

   The unjust execution was the signal for revolt.

4. a token; indication.

   Synonyms:

   sign

5. Electronics. an electrical quantity or effect, as current, voltage, or electromagnetic waves, that can be varied in such a way as to convey information.

6. Cards. a play that reveals to one's partner a wish that they continue or discontinue the suit led.

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adjective

1. serving as a token or indication; used in communiating an intention, warning, or command.

   a signal flag.

2. unusual; notable; outstanding.

   a signal exploit.

   Synonyms:

   striking, remarkable, exceptional, unique

verb (used with object)

signaled, signaling, signalled, signalling

1. to make a token or indication to.

2. to communicate or make known by a token or indication.

verb (used without object)

signaled, signaling, signalled, signalling

1. to make communication by something that serves to indicate, warn, direct, command, or the like.

signal British  

/ ˈsɪɡnəl /

noun

1. any sign, gesture, token, etc, that serves to communicate information

2. anything that acts as an incitement to action

   the rise in prices was a signal for rebellion

3. 1. a variable parameter, such as a current or electromagnetic wave, by which information is conveyed through an electronic circuit, communications system, etc

   2. the information so conveyed

   3. ( as modifier )

      signal strength

      a signal generator

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adjective

1. distinguished or conspicuous

2. used to give or act as a signal

verb

1. to communicate (a message, etc) to (a person)

signal Scientific  

/ sĭg′nəl /

1. A fluctuating quantity or impulse whose variations represent information. The amplitude or frequency of voltage, current, electric field strength, light, and sound can be varied as signals representing information.

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Other Word Forms

• presignal noun
• resignal verb
• signaler noun
• signaller noun
• unsignaled adjective
• unsignalled adjective

Etymology

Origin of signal

First recorded in 1350–1400; Middle English noun from Old French seignal, signal, from Medieval Latin signāle, Late Latin, noun use of neuter of signālis “of a sign”; sign, -al ², -al ¹

Example Sentences

"Might have gotten cut off," Trump said as he waited a full minute for the signal to return.

From Barron's • Apr. 7, 2026

Instead, a more helpful framework is to interpret the curve as a signal to help traders and end users of oil manage their inventories.

From MarketWatch • Apr. 7, 2026

To identify promising candidates, the team tested about 500 compounds using a specially engineered hepatitis E virus that produces a fluorescent signal.

From Science Daily • Apr. 6, 2026

The warm embrace was a signal that the de facto Saudi leader, once shunned in the West, was fully rehabilitated on the world stage.

From The Wall Street Journal • Apr. 6, 2026

I stop fretting about my phone signal and the flight from Santa Fe.

From "Legendary Frybread Drive-In" by Cynthia Leitich Smith

Related Words

• alarm
• beacon
• cue
• gesture
• indicator
• sign