<communications> Any part of a signal that is not the true or original signal but is introduced by the communication mechanism.

A common example would be an electrical signal travelling down a wire to which noise is added by inductive and capacitive coupling with other nearby signals (this kind of noise is known as "crosstalk").

A less obvious form of noise is quantisation noise, such as the error between the true colour of a point in a scene in the real world and its representation as a pixel in a digital image.

(01 Aug 2003)

1. Sound of any kind. "The heavens turn about in a most rapid motion without noise to us perceived." (Bacon)

Noise is either a sound of too short a duration to be determined, like the report of a cannon; or else it is a confused mixture of many discordant sounds, like the rolling of thunder or the noise of the waves. Nevertheless, the difference between sound and noise is by no means precise.

2. Especially, loud, confused, or senseless sound; clamor; din.

3. Loud or continuous talk; general talk or discussion; rumor; report. "The noise goes." "What noise have we had about transplantation of diseases and transfusion of blood!" (T. Baker) "Soerates lived in Athens during the great plague which has made so much noise in all ages." (Spectator)

4. Music, in general; a concert; also, a company of musicians; a band. "The king has his noise of gypsies." (B. Jonson)

Synonyms: Cry, outcry, clamor, din, clatter, uproar.

Origin: F. Noise noisy strife, quarrel, brawl, fr. L. Nausea seasickness, sickness, disgust. See Nausea.

(01 Mar 1998)