grityoudaoicibaDictYouDict[grit 词源字典]
grit: [OE] Etymologically, grit is ‘something produced by pounding’. Prehistoric Indo- European *ghrēu- denoted ‘rub, pound, crush’, and from it came Germanic *greutam ‘tiny particles of crushed or pounded rock’, hence ‘sand, gravel’. Its modern descendants include English grit and German griess ‘gravel, grit, coarse sand’, and it was also used in the formation of the Old English word for ‘pearl’, meregrot, literally ‘sea-pebble’, an alteration of Latin margarīta ‘pearl’. Groats ‘husked grain’ [OE] comes from the same source.

The sense ‘determination, resolve’ originated in the USA in the early 19th century, presumably as a metaphorical extension of grit meaning ‘hard sandstone’ (as in millstone grit).
=> groats[grit etymology, grit origin, 英语词源]
grit (n.)youdaoicibaDictYouDict
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, 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]
grit (v.)youdaoicibaDictYouDict
"make a grating sound," 1762, probably from grit (n.). Meaning "to grate, grind" is from 1797. Related: Gritted; gritting.