Abstract
The survey covers the scientific thoughts of one of the founders of Kazakh linguistics, scientist K. Zhubanov, concerning grammar. About the features of language functions, definitions and terms of grammatical categories and their differences between them in other textbooks. While word formation is one of the main problems in morphology, in the formation of the theoretical principles of word formation it is said that the thoughts expressed in the works of the scientist coincide with modern positions. The work «grammar of the Kazakh language» emphasizes that the terms of linguistics are still used in modern scientific textbooks to define and theoretically describe grammatical categories, grammar is science, word-personality, word-thought, sentence, and provides evidence that the members of a sentence, a dead root, a compound word, a derivative basis etc. they used terms, gave them definitions and conducted a scientific analysis. There was also a scientific proof of why the term «suffix» in modern scientific textbooks was called «adverb», giving specific examples to it, dividing words into six types depending on the characteristics of their external personality. A comprehensive analysis of the theoretical features of scientific categories in the field of morphology of linguistics, its connection with terms, is carried out, and subsequent textbooks give an idea that morphology has a scientific basis for recognizing categories and creating their definitions.