Old English greot "sand, dust, earth, gravel," from Proto-Germanic *greutan "tiny particles of crushed rock" (source also of Old Saxon griot, Old Frisian gret, Old Norse grjot "rock, stone," German Grieß "grit, sand"), from PIE *ghreu- "rub, grind" (source also of Lithuanian grūdas "corn, kernel," Old Church Slavonic gruda "clod"). Sense of "pluck, spirit, firmness of mind" first recorded American English, 1808.
If he hadn't a had the clear grit in him, and showed teeth and claws, they'd a nullified him so, you wouldn't have see'd a grease spot of him no more. [Thomas Chandler Haliburton, "Sam Slick in England," 1843]
In American English, corn-based grits and hominy (q.v.) were used interchangeably in Colonial times. Later, hominy meant whole kernels that had been skinned but not ground, but in the U.S. South, hominy meant skinned kernels that could be ground coarsely to make grits. In New Orleans, whole kernels are big hominy and ground kernels little hominy.
in reference to color, "intensity of distinctive hue, degree of departure of a color-sensation from that of white or gray," 1889, from Latinized form of Greek khrōma "surface of the body, skin, color of the skin," also used generically for "color" and, in plural, "ornaments, make-up, embellishments," a verbal noun from khroizein "to color, stain, to touch the surface of the body," khrosthenai "to take on a color or hue," from khros, khroia "surface of the body, skin."
Beekes considers this noun to be of uncertain origin. It sometimes is explained as being somehow from PIE *ghreu- "to rub, grind" (see grit (n.)).
"small particle, as of dust visible in a ray of sunlight," Old English mot, of unknown origin; perhaps related to Dutch mot "dust from turf, sawdust, grit," Norwegian mutt "speck, mote, splinter, chip." Hence, anything very small. Many references are to Matthew vii.3.