* A grammarian: This is the most common meaning. A grammatistes is someone who studies grammar and language, or who is an expert in the rules of grammar.
* A teacher of grammar: This meaning is closely related to the first. It refers to someone who teaches grammar, either formally or informally.
* A writer or poet: In ancient Greece, the term could also refer to a writer or poet, as grammar was considered an essential part of literary composition.
It's important to consider the context in which "grammatistes" is used to determine the most accurate interpretation.