A set of three of a kind or three united.

三物一组；三体联合。

Three lines riming together.

【诗】同押一韵之三行。

Three notes sounded in the time of two.

【乐】三连音符。

One of three children at one birth.

三胞胎之一。

A group of three elementary particles (as positive, negative, and neutral pions) with different charge states but otherwise similar properties.

三重线(三种基本粒子合成的一组，如正 π 介子、负介子和中性 π 介子等，电荷位不同，但其他性质相似)。