1. a range of frequencies, usually expressed in hertz (cycles per second). In information theory, it is a measure of the amount of information that a communication channel can transmit per unit of time.

2. the range of information available from measuring instruments. Greater bandwidth is generally associated with lower accuracy (fidelity).

3. a window or range of data values that contains a point of interest. The term is often used in nonparametric regression and estimation problems.