Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary


noun sig·nal \ˈsig-nəl\

Simple Definition of signal

  • : an event or act which shows that something exists or that gives information about something

  • : something (such as a sound, a movement of part of the body, or an object) that gives information about something or that tells someone to do something

  • : a piece of equipment with colored lights that is used on railways and roads to tell people when to go, to slow down, or to stop

Full Definition of signal

  1. 1 :  sign, indication

  2. 2a :  an act, event, or watchword that has been agreed on as the occasion of concerted actionb :  something that incites to action

  3. 3 :  something (as a sound, gesture, or object) that conveys notice or warning

  4. 4a :  an object used to transmit or convey information beyond the range of human voiceb :  the sound or image conveyed in telegraphy, telephony, radio, radar, or televisionc :  a detectable physical quantity or impulse (as a voltage, current, or magnetic field strength) by which messages or information can be transmitted

Examples of signal

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

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

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

Origin of signal

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

First Known Use: 14th century



verb sig·nal

Simple Definition of signal

  • : to be a sign of (something) : to show the existence of (something)

  • : to make a sound or motion that tells someone something

Full Definition of signal

sig·naled or sig·nalledsig·nal·ing or sig·nal·ling play \-nə-liŋ\

  1. transitive verb
  2. 1 :  to notify by a signal <signal the fleet to turn back>

  3. 2a :  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)

  4. intransitive verb
  5. :  to make or send a signal

sig·nal·er or sig·nal·ler noun

Examples of signal

  1. Robins signal the arrival of spring.

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

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

  4. Did he signal before he made the left turn?

  5. They signaled at me to come over to their table.

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

  7. The umpire signaled a strike.


First Known Use of signal




adjective sig·nal

Simple Definition of signal

  • : very important or great

Full Definition of signal

  1. :  distinguished from the ordinary :  notable <a signal achievement>

Examples of signal

  1. Is he worthy of such a signal honor?

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

Origin of signal

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: 1627

Seen and Heard

What made you want to look up signal? Please tell us where you read or heard it (including the quote, if possible).


February 6, 2016

an official order, decree, or edict

Get Word of the Day daily email!


Take a 3-minute break and test your skills!


Which of the following refers to thin, bending ice, or to the act of running over such ice?

spindrift pince-nez kittly-benders duvet
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.


Test Your Knowledge - and learn some interesting things along the way.