Vocabulary is a list or collections of words as in the words used by a person, a language, or a group. Conservapedia focuses encyclopedic entries for high school students, therefore it uses an appropriate "vocabulary" of words students would know.
All languages have vocabularies that are in constant flux. Words come and go in the language even if they are not formally recognized by any group. Some organizations or fields of study, like the legal field for example, have specialized vocabulary that the population at large is not generally expected to know.
The average High school student vocabulary is roughly 10,000 words. The SAT tests for approximately 35,000 words. Shakespeare knew nearly double that amount.[1]