Here are some common technical terms used to describe the different parts of a cable.

Conductor - Carries the audio signal. A single conductor carries 1 channel of audio.

 Shield - Carries the ground signal that all electrical components must have. When used describing cable, it refers to a served (spiral), or in some cases braided, shield. The shield is the second layer from the jacket of the cable, surrounding the conductor wires.

 Coaxial - Refers to the configuration of a cable which has one or more conductors in the center, surrounded by and insulated from a shield, which carries the electrical ground. This configuration elminates most EMI and RFI (see below) interference, making it the most ideal configuration for low-voltage cables.

 Balanced - Stereo (two channels), plus shield. When used to describe cable, balanced means 2-conductor. In the case of audio cables, a balanced configuration has an additional shield.

 Unbalanced - Mono (single channel), plus shield. When used to describe cable, unbalanced means single-conductor. In the case of audio cables, an unbalanced configuration has an additional shield and is coaxial.

 Quad - A term referring to 4-conductor (plus shield) cable, which is mostly used in balanced cables. Quad cable generates a perfect electromagnetic field, which is much more closed to electromagnetic interference than standard 2-conductor cable.
Each 2 conductors are soldered to 1 channel of a connector, for a total of 2 channels of audio.

 Hi-Z - Denotes low voltage application, in which the cable has a low voltage signal running through it. Basically, this would be any current you couldn't hear over speakers without amplifying it.

 Lo-Z - Denotes higher voltage application, in which the cable is carrying a high-load signal, such as from amplifier to speaker.

 TRS - Tip-Ring-Sleeve (Stereo). Refers to the three contact areas of a balanced 1/4" connector. Balanced 1/8" "Mini" connectors are also referred to this way.
The tip of the connector carries the left (in-phase, "hot") channel audio signal, the ring carries the right (out-of-phase, "cold") channel audio signal, and the sleeve is the electrical ground (The ground prevents noise and electromagnetic interference).

 TS - Tip-Sleeve (Mono). Refers to the two contact areas of an unbalanced 1/4" connector. Unbalanced 1/8" "Mini" connectors are also referred to this way.
The tip of the connector carries the audio signal, while the sleeve is the electrical ground.

 XLR - A 3-pin balanced connector used widely in studios, such as for microphones.

 1/4" - Refers to a connector with a 1/4" thick barrel.

 EMI - Electro-Magnetic Interference. EMI can cause noise and distortion in an audio signal. A cable's shield is its main protection against EMI.
The cable most immune to EMI is quad cable (read above).

 RFI - Radio Frequency Interference. Comes from any source that emits radio waves, as well as others that inadvertantly create RF noise, such as desktop PCs.