Definition of grammar
1a
: the study of the classes of words, their inflections (see inflection sense 2), and their functions and relations in the sentence
b
: a study of what is to be preferred and what avoided in inflection (see inflection sense 2) and syntax (see syntax sense 1)
2a
: the characteristic system of inflections (see inflection sense 2) and syntax of a language
b
: a system of rules that defines the grammatical structure of a language
3a
: a grammar textbook
b
: speech or writing evaluated according to its conformity to grammatical rules
appalled at the bad grammar of college students
4
: the principles or rules of an art, science, or technique
a grammar of the theater
also
: a set of such principles or rules
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Merriam-Webster unabridged
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The first known use of grammar was in the 14th century
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