n. 1. a. An indicator, such as a gesture or colored light, that serves as a means of communication. See Synonyms at gesture. b. A message communicated by such means. 2. Something that incites action: The peace treaty was the signal for celebration. 3. Biology A physical entity, such as a chemical or an electromagnetic wave, that activates a cell receptor and elicits a specific response. 4. a. Electronics An impulse or fluctuating quantity, as of electrical voltage or light intensity, whose variations represent coded information. b. Computers A sequence of digital values whose variations represent coded information. 5. The sound, image, or message transmitted or received by means of telecommunications. adj. Notably out of the ordinary: a signal feat; a signal event. v. sig·naled, sig·nal·ing, sig·nals or sig·nalled or sig·nal·ling v.tr. 1. To make a signal to: I signaled the driver to proceed. 2. To relate or make known by signals: They have signaled their willingness to negotiate. 3. To cause an effect in (a cell) by the activation of a receptor, as by a neurotransmitter or hormone. v.intr. To make a signal or signals. [Middle English, from Old French, from Medieval Latin signāle, from neuter of Late Latin signālis, of a sign, from Latin signum, sign; see SIGN.] signal·er, signal·ler n. |
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