It should be spelt as "g-r-a-m-m-a-r".
Descriptive grammar does not distinguish between correct and incorrect usage, whereas prescriptive grammar does make the distinction.
That easy. You not any kind of verb in your sentence. That it.
No, grammar is spelled grammar in the U.S.
1. a particular analysis of the system and structure of language or of a specific language. 2. the whole system and structure of a language or of languages in general, usually taken as consisting of...