- An abbreviation of bel, the logarithm of the ratio of two powers. The decibel is one tenth of a bel.
- The bel is the logarithm of the ratio of two powers, and the decibel is one tenth of a bel.
- The human ear responds logarithmically and it is convenient to deal in logarithmic units in audio systems.
- The electrical resistance of a conductor.
- Passive component with a known resistance. The value of resistance is usually shown by a set of coloured bands on the body of the component.