signal

UK: /ˈsɪgnəl/ US: /ˈsɪgnəl/ ,(sig′nl)

Inflections of 'signal' (v): (⇒ conjugate)

When both "l" and "ll" forms exist, spellings with a double "l" are correct, but rare, in US English, while those with a single "l" are not correct in UK English.

signals

v 3rd person singular

signalling

v pres p (Mainly UK)

signaling

v pres p (US)

signalled

v past (Mainly UK)

signaled

v past (US)

signalled

v past p (Mainly UK)

signaled

v past p (US)

WordReference Random House Learner's Dictionary of American English © 2025

sig•nal /ˈsɪgnəl/   n., adj., v., -naled, -nal•ing or (esp. Brit.) -nalled, -nal•ling. 
n. [countable]

1. anything that serves to indicate, warn, direct, etc., such as a light, a gesture, or an act:
   a traffic signal.
2. an act or event that causes an action:
   The execution was a signal for revolt.
3. Electronics an electrical quantity or effect, as current or waves, that can be varied to convey information:
   a TV signal.

adj. [before a noun]

4. serving as a signal:
   a signal light.
5. unusual;
   notable;
   outstanding:
   a signal accomplishment.

v. 

6. to make a signal to (someone or something): [no object]
   The police officer stood there signaling.
   [~ + object]
   The captain said he wanted to signal his ship.
   [~ + object + to + verb]
   Signal the tugboat to pull up a little closer.
   [~ + that clause]
   to signal that he wants to come home.

See -sign-.

WordReference Random House Unabridged Dictionary of American English © 2025

sig•nal  (sig′nl), n., adj., v., -naled, -nal•ing or (esp. Brit.) -nalled, -nal•ling. 
n. 

1. anything that serves to indicate, warn, direct, command, or the like, as a light, a gesture, an act, etc.:
   a traffic signal; a signal to leave.
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.
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. Games [Cards.] a play that reveals to one's partner a wish that he or she continue or discontinue the suit led.

adj. 

7. serving as a signal;
   used in signaling:
   a signal flag.
8. unusual;
   notable;
   outstanding:
   a signal exploit.

v.t. 

9. to make a signal to.
10. to communicate or make known by a signal.

v.i. 

11. to make communication by a signal or signals.

• Medieval Latin signāle, Late Latin, noun, nominal use of neuter of signālis of a sign. See sign, -al², -al¹
• Middle English (noun, nominal) 1350–1400

sig′nal•er;
 esp. Brit. sig′nal•ler, n. 
Synonyms

• 1, 4. sign.
• 8. unique, exceptional, remarkable, striking.

Collins Concise English Dictionary © HarperCollins Publishers::

signal / ˈsɪɡn^əl/ 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. a variable parameter, such as a current or electromagnetic wave, by which information is conveyed through an electronic circuit, communications system, etc
4. the information so conveyed
5. (as modifier): signal strength, a signal generator

adjective

1. distinguished or conspicuous
2. used to give or act as a signal

verb ( -nals, -nalling, -nalled) ( -nals, -naling, -naled)

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

Etymology: 16th Century: from Old French seignal, from Medieval Latin signāle, from Latin signum sign

ˈsignaller, ˈsignaler noun