the study of the classes of words, their inflections, and their functions and relations in the sentence; broadly this study when taken to include that of phonology and sometimes of usage
the characteristic system of inflections and syntax of a language
a grammar textbook
speech or writing evaluated according to its conformity to grammatical rules
No one in the world speaks blemishless grammar — Mark Twain
the principles or rules of an art or, science, or technique
[Middle English gramere from early French gramaire, modification of Latin grammatica, ultimately from Greek grammatikos, grammat-, gramma letter of the alphabet, writing, a small weight, from graphein to write]