grit

(noun) a hard coarse-grained siliceous sandstone. Synonyms: gritrock, gritstone.

(noun) fortitude and determination. Synonyms: backbone, guts, moxie, sand, gumption. Example: "He didn't have the guts to try it."

(verb) cover with a grit. Example: "Grit roads."

(verb) clench together. Example: "Grit one's teeth."