duplex (Adjective) — (used technically of a device or process) having two parts. ex. "a duplex transaction"
duplex (Adjective) — (telecommunication) allowing communication in opposite directions simultaneously. ex. "duplex system" ex. "duplex telephony"
duplex (Noun) — A house with two units sharing a common wall.
duplex (Noun) — An apartment having rooms on two floors that are connected by a staircase.
duplex (Verb) — Change into a duplex.