- Unwanted sound, particularly a complex sound that lacks a musical quality because its various frequencies that comprise it are not whole-or-partial number multiples (harmonics) of each other.
- Unwanted additions to a signal not arising at its source; the 60-cycle frequency wave in an electrocardiogram; largely eliminated from machines after 1980 (includes visual noise on imaging studies).
- Extraneous uncontrolled variables influencing the distibution of measurements in a set of data.
See: signal:noise ratio
[M.E., fr. O.Fr., fr. L.L. nausea, seasickness]