1
- something having two parts, in particular成对物, 成双物, 双重物, 尤指：
1.1
- a flat on two floors复式公寓, 占两层楼的公寓套房。
1.2
- N. Amer. a residential building divided into two apartments〈北美〉联式房屋, 分为两套公寓的住房。
1.3
- chiefly N. Amer. & Austral. a semi-detached house〈主北美, 澳〉半独立式房屋。
1.4
- Biochemistry a double-stranded polynucleotide molecule【生化】双股多（聚）核苷酸分子。
1
- having two parts, in particular双的, 双重的, 尤指：
(of a flat or room) on two floors
（公寓或房间）复式的, 占两层楼的。
1.1
- chiefly N. Amer. & Austral. (of a house) semi-detached〈主北美, 澳〉（房屋）半独立式的。
1.2
- (of paper or board) having two differently coloured layers or sides（纸, 卡板纸）双层的, 双面的。
1.3
- Biochemistry consisting of two polynucleotide strands linked side by side【生化】双螺旋的, 双股的。
1.4
- (of a printer or its software) capable of printing on both sides of the paper（打印机或其软件）可双面打印的。
2
- (of a communications system, computer circuit, etc.) allowing the transmission of two signals simultaneously in opposite directions（通信系统或计算机电路等）允许两个信号同时反方向传送的, 双工的, 双向的。
词源
mid 16th cent. (as an adjective)： from Latin duplex, duplic-, from duo 'two' + plicare 'to fold'. The noun dates from the 1920s.