In science, and especially in physics and telecommunication, noise is random fluctuations and the addition of external factors to the stream of target information (signal) being received at a detector.
More specifically, in physics, the term noise has the following meanings:
3. Random variations of one or more characteristics of any entity such as voltage, current, or data.
4. A random signal of known statistical properties of amplitude, distribution, and spectral density.
5. Loosely, any disturbance tending to interfere with the normal operation of a device or system.