Say it right in English. Do not say vocabulary. Say instead vocabulary words or vocabulary. Vocabulary is usually uncountable. It refers to an entire set of words. Say vocabulary when you are speaking generally. For example, English vocabulary is not difficult. When you want to refer to a single word or many words say vocabulary words. For example, I learned five new vocabulary words today. One vocabulary word, two vocabulary words, five vocabulary words. To learn more about this topic, see video at link. Or check out our websites for more free English learning resources. ESLgold.com or free English study.com