n. & adj.
--n. esp. US 1 a flat or maisonette on two levels.
2 a house subdivided for two families.
--adj.
1. having two elements; twofold.
2 esp. US a (of a flat) two-storeyed. b (of a house) for two families.
3 Computing (of a circuit) allowing the transmission of signals in both directions simultaneously (opp. SIMPLEX).
Phrases and idioms:
half-duplex Computing (of a circuit) allowing the transmission of signals in both directions but not simultaneously.
Etymology: L duplex duplicis f. duo two + plic- fold