Having two parts or aspects; double.

• Designed for or involving two functions, users, or modes.
• Belonging to two at once, as in dual citizenship.
• In some languages, expressing the grammatical number two.

有两个部分或方面的；双重的。

• 涉及两件事物的；成对的。

A counterpart related by duality, especially in mathematics.

• The dual space or dual object of a structure.
• A head-to-head meet between two teams.

表示恰好两个的语法数。

To convert a single carriageway into a dual carriageway.

为另一对象的对偶；呈现对偶性。

• 向量空间的对偶空间，即所有线性泛函的集合。

两支队伍之间的直接对抗赛。

由对偶关系得到的对应物。

• 对偶空间。

将单车道公路改建为分隔的双车道公路。