1
a: the study of the classes of words, their inflections, and their functions and relations in the sentence
b: a study of what is to be preferred and what avoided in inflection and syntax
2
a: the characteristic system of inflections and syntax of a language
b: a system of rules that defines the grammatical structure of a language
3
a: a grammar textbook
b: speech or writing evaluated according to its conformity to grammatical rules
4
: the principles or rules of an art, science, or technique ; also: a set of such principles or rules