Meaning of “grind” - Learner’s Dictionary

grind

verb [ T ] uk us /ɡraɪnd/ (past tense and past participle ground)
MAKE INTO POWDER

to keep rubbing something between two rough, hard surfaces until it becomes a powder:

to grind coffee
MAKE SHARP

to rub a blade against a hard surface to make it sharp

grind your teeth

to rub your teeth together, making an unpleasant sound

(Definition of “grind verb” from the Cambridge Learner’s Dictionary © Cambridge University Press)