Referring to a metallic wire cable used to connect two computers directly without the use of modems. A null modem cable simply crosses the transmit and receive wires so that the wire used by one machine for signal transmission is used by the other machine for signal reception.A null modem cable can be created by manually crossing the wires. Alternatively, a null modem adapter can be used to accomplish the necessary crosslinks. (Note: A null modem is much less expensive and much prettier.) See also cable, modem, and wire.