signal

1 of 3

noun

sig·​nal ˈsig-nᵊl 

1

: sign, indication

2

a

: an act, event, or watchword that has been agreed on as the occasion of concerted action

b

: something that incites to action

3

: something (such as a sound, gesture, or object) that conveys notice or warning

4

a

: an object used to transmit or convey information beyond the range of human voice

b

: the sound or image conveyed in telegraphy, telephony, radio, radar, or television

c

: a detectable physical quantity or impulse (such as a voltage, current, or magnetic field strength) by which messages or information can be transmitted

signal

2 of 3

verb

signaled or signalled; signaling or signalling ˈsig-nə-liŋ 

transitive verb

1

: to notify by a signal

signal the fleet to turn back

2

a

: to communicate or indicate by or as if by signals

signaled the end of an era

b

: to constitute a characteristic feature of (a meaningful linguistic form)

intransitive verb

: to make or send a signal

signaler noun

or signaller

signal

3 of 3

adjective

: distinguished from the ordinary : notable

a signal achievement

Synonyms

Noun

• flag

Verb

• motion
• wave
• gesture

Adjective

• outstanding
• distinguished
• prestigious
• notable

Examples of signal in a Sentence

Noun

He likes her but he is sending the wrong signals with his constant teasing.

The teacher gave us the signal to finish what we were working on and hand in our tests.

Faulty wiring in the train station caused a signal to malfunction.

Verb

Robins signal the arrival of spring.

The election results surely signal the start of a new era.

A lock on the suitcase might signal that there's something of value inside.

Did he signal before he made the left turn?

They signaled at me to come over to their table.

He signaled us that it was time to begin the meeting.

The umpire signaled a strike.

Adjective

Is he worthy of such a signal honor?

the Louisiana Purchase is cited by many historians as one of the most signal events in American history

Recent Examples on the Web

Noun

When proteins are modified, the glow provides a visual signal, letting researchers monitor biological activity without breaking open cells or adding disruptive chemicals. —Neetika Walter, Interesting Engineering, 24 Oct. 2025

If the Fed cuts rates deeper than expected, Sohn said, Wall Street could interpret the move as a signal that the Fed is worried that the economy is heading into a recession. —Susan Tompor, Freep.com, 23 Oct. 2025

Verb

The warnings also underscore the early arrival of winter weather, signaling that colder, stormier conditions are setting in across much of the region. —Martha McHardy, MSNBC Newsweek, 25 Oct. 2025

Most aneurysms are symptom-free, but sudden severe headaches or vision changes can signal a life-threatening rupture. —Sohaib Imtiaz, Health, 25 Oct. 2025

Word History

Etymology

Noun

Middle English, from Medieval Latin signale, from Late Latin, neuter of signalis of a sign, from Latin signum

Adjective

modification of French signalé, past participle of signaler to distinguish, from Old Italian segnalare to signal, distinguish, from segnale signal, from Medieval Latin signale

First Known Use

Noun

15th century, in the meaning defined at sense 1

Verb

1800, in the meaning defined at transitive sense 1

Adjective

1591, in the meaning defined above

Phrases Containing signal

• distress signal
• distress signal/call
• hand signal
• signal-caller
• sound/signal the retreat
• traffic signal
• turn signal
• virtue-signal

Kids Definition

signal

1 of 3 noun

sig·​nal ˈsig-nᵊl 

1

: an act, event, or word that serves to start some action

2

: a sound or motion of a part of the body made to give warning or command

3

: an object placed to give notice or warning

a traffic signal

4

a

: the message, sound, or effect transmitted in electronic communication (as radio or television)

b

: a radio wave or electric current that transmits a message or effect (as in radio or television)

signal

2 of 3 verb

signaled or signalled; signaling or signalling -nə-liŋ 

1

: to notify by a signal

2

: to communicate by or as if by signals

signaler noun

signal

3 of 3 adjective

1

: unusually great

a signal honor

a signal achievement

2

: used in signaling

a signal light

signally

-nə-lē

adverb

Etymology

Noun

Middle English signal "signal, sign," derived from Latin signalis "of a sign," from earlier signum "mark, sign, image" — related to sign