对句（Couplet），又称二行连句，由相连并押韵的两行诗组成，讲究韵律。

传统的对句都讲究押韵，但并非所有的对句都是如此。如果诗歌不押韵，可以在空白的地方标示出对句。五音步抑扬格的对句被称为英雄对句，警句也属于对句。对句中也可以出现更复杂的韵律，如莎士比亚的十四行诗以一副对句结束。

押韵的对句是最简单的诗韵之一。杰弗里·乔叟的《坎特伯雷故事集》就含有押韵的对句。17世纪的约翰·德莱顿和18世纪的亚历山大·蒲柏以写英雄对句而闻名。

在押韵的对句中，韵律往往是关注的重点。这样的对句有：

A couplet is a pair of lines of metre in poetry. Couplets usually comprise two lines that rhyme and have the same metre. A couplet may be formal (closed) or run-on (open). In a formal (or closed) couplet, each of the two lines is end-stopped, implying that there is a grammatical pause at the end of a line of verse. In a run-on (or open) couplet, the meaning of the first line continues to the second.