Channel

1. A connection between initiating and terminating nodes of a circuit.

2. A single path provided by a transmission medium via either (a) physical separation, such as by multipair cable or (b) electrical separation, such as by frequency- or time-division multiplexing.

3. A path for conveying electrical or electromagnetic signals, usually distinguished from other parallel paths.

4. Used in conjunction with a predetermined letter, number, or codeword to reference a specific radio frequency.

5. The portion of a storage medium, such as a track or a band, that is accessible to a given reading or writing station or head.

6. In a communications system, the part that connects a data source to a data sink.

Source: from Federal Standard 1037C and from MIL-STD-188

A channel, in physical geography, is another name for a strait, which is a narrow channel of water that connects two larger bodies of water. The terms strait, channel, and passage are synonymous and are usually interchangeable.