General English

  • verb to make signs to tell someone to do something


  • noun a device, action or sound which passes information


  • verb to send warning messages about something



  • aggregate waves that are transmitted or received.


  • Anything, such as a light, sound, location, or movement, which serves to convey information.
  • A varying quantity, state, or parameter which serves to convey information. For example, a fluctuating amplitude, frequency, or waveform, a series of tones, flashing lights, field strength variations, changes in pulse duration, and so on. Used, for instance, in communications, for sending control signals, to activate processes, to alert to a given condition, and so on.
  • A fluctuating electrical quantity, such as a current or voltage, which serves as a signal (2).
  • The sounds, images, data, or other information transmitted and/or received in communications, radio, TV, radar, and so on.
  • A specific signal (1) or signal (2), such as a busy signal, a carrier signal, or a chrominance signal.

Information & Library Science

  • noun a way of sending a message over a distance by physical or electronic methods

Media Studies

  • noun information transmitted by means of a modulated current or an electromagnetic wave and received by telephone, telegraph, radio or television


  • noun a sign made by flags, gestures, light or any other means, in order to convey information or instructions
  • noun the electromagnetic waves transmitted by a radio transmitter
  • verb to make a sign, in order to convey information or instructions


  • noun a movement of the hand or head which tells someone to do something
  • noun a light or mechanical flag used to tell someone to do something

Origin & History of “signal”

Latin signālis meant ‘of a sign’ (it was derived from signum ‘mark, token’, source of English sign). It came to be used as a noun, and passed via medieval Latin signāle into Old French as seignal. this was later relatinized into signal, in which form it was taken over by English. The adjective signal ‘conspicuous’ came from the same ultimate source, but via a more circuitous route. The Italian version of the noun signal is segnale. From it was derived the verb segnalare ‘make famous’, whose past participle segnalato gave French signalé – whence English signal.