1 one of two children or animals that are born to one mother at the same time 双胞胎或孪生子中的一个:
They're very alike. Are they twins?他们长得很像,是不是孪生儿?a twin brother/sister孪生兄弟╱姐妹identical twins单卵双胞胎☞Look at Siamese twin and triplet. 参看Siamese twin及triplet。
2 one of a pair of things that are the same or very similar 两个相同或非常相似的事物中的一个:
twin engines双引擎twin beds成对的单人床☞Look at the note at bed ¹. 参看bed^1的注释。