1 [C,U] all the words that sb knows or that are used in a particular book, subject, etc （一个人掌握的或某书、某学科等中使用的）词汇量，词汇: He has an amazing vocabulary for a five-year-old. 以一个五岁儿童来说，他所掌握的词汇量相当惊人。There are many ways to increase your English vocabulary. 有许多方法可以增加英语词汇量。

2 [sing] all the words in a language （一种语言的）词汇，字汇: New words are always coming into the vocabulary. 新词不断加入，丰富现有的词汇。