The type of wire used by the phone company to wire telephones -- at least over distances like between your house and the central office. It has two conductors, which are twisted. The twists are important: they give it electrical characteristics which allow some kinds of communications otherwise not possible. Ordinary telephone cables are not shielded (see Shielded Twisted-Pair).

[Source: BIG-LAN Digest, Volume 5, Number 67, Friday, November 5, 1993]