. Communication: Anything that interferes with, slows down, or reduces the clarity or accuracy of a communication. Thus, superfluous data or words in a message are noise because they detract from its meaning.
2. Quality control: Variability that may be caused by changes in the ambient conditions, faulty machine performance, or uneven quality of the material or human factor inputs.
3. Telecommunications: Random disturbance introduced into a communication signal, caused by circuit components, electromagnetic interference, or weather conditions. Also called line noise.