Old English greot "sand, dust, earth, gravel," from Proto-Germanic *greutan "tiny particles of crushed rock" (cognates: Old Saxon griot, Old Frisian gret, Old Norse grjot "rock, stone," German Grieß "grit, sand"), from PIE *ghreu- "rub, grind" (cognates: Lithuanian grudas "corn, kernel," Old Church Slavonic gruda "clod"). Sense of "pluck, spirit" first recorded American English, 1808.

"make a grating sound," 1762, probably from grit, n.. Related: Gritted; gritting.