1. [adj]  responding to or operating at a wide band of frequencies; "a broadband antenna"
2. [adj]  of or relating to or being a communications network in which the bandwidth can be divided and shared by multiple simultaneous signals (as for voice or data or video)

A transmission medium capable of supporting a wide range of frequencies, typically from audio up to video frequencies. It can carry multiple signals by dividing the total capacity of the medium into multiple, independent bandwidth channels, where each channel operates only on a specific range of frequencies.

See also baseband.