Watch the video to learn how to use these forms correctly.
The word "vocabulary" is a non-count (uncountable) noun in English. It refers to the total set of words or terms used in a language, profession, subject, or by an individual person. We cannot count "vocabulary" because it is an abstract idea and cannot be divided into separate units. For example, we can say, "I have a good vocabulary" or "I need to improve my vocabulary," but we cannot say "I have two vocabularies" or "I learned ten vocabularies today." However, we can talk about specific words in a vocabulary, which are counted as individual units.