IPA: /ɡrəˈmætɪkəlɪti/
KK: /grəˈmætɪkəlɪti/
The quality of being correct according to the rules of a language's grammar.
The grammaticality of her sentences impressed the teacher.
Grammaticality → It is formed from "grammatical" (from Greek "grammatikos", meaning pertaining to letters or writing) and the suffix "-ity" (meaning the state or quality of). The word "grammaticality" refers to the state or quality of being grammatical or conforming to the rules of grammar.
Think of the word 'grammatical' which relates to the rules of language, and remember that 'grammaticality' means the quality of following those rules.