Grammar meaning : A system of rules and principles for speaking and writing a language. The study of the internal structure of words (morphology) and the use of words in the construction of phrases and sentences (syntax). A book describing the rules of grammar of a language. A formal system specifying the syntax of a language. Actual or presumed prescriptive notions about the correct use of a language. A formal system defining a formal language The basic rules or principles of a field of knowledge or a particular skill. A textbook. A grammar school. To discourse according to the rules of grammar; to use grammar.