1. A collection or list of terms with brief explanations of their meanings: A vocabulary is a complete word stock of a language; an extensive body of verbal elements used when speaking, reading, or writing as a group, a class, or by individuals.
2. The range, or extent, of statements associated with a subject or area of activity, or used by a particular person, class, profession, etc.: One's vocabulary is considered to be a scope of expressions and an extensive range of linguistic communications.

A good way to improve one's vocabulary is to learn more about their roots or sources of where they come from.

3. The sum, or aggregate, of elements composing a language, or languages: Vocabularies consist of lists of words; usually, defined and alphabetized, as in dictionaries, specialized glossaries, etc.; all of which are used to make it possible for people to communicate better with each other.

4. Etymology: a stock of words from 1532, in the writing of Sir Tomas More; perhaps borrowed by influence of Middle French vocabulaire, which came from Medieval Latin vocabularium, "a list of words"; from Latin vocabulum, "a word, a name"; from vocare, "to name, to call".
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