n. 25B6; verb
the sandstone is ground into powder : CRUSH, pound, pulverize, mill, granulate, crumble, smash, press; technical triturate, comminute; archaic levigate, bray.
a knife being ground on a wheel : SHARPEN, whet, hone, file, strop; smooth, polish, sand, sandpaper.
one tectonic plate grinds against another : RUB, grate, scrape, rasp.
25B6; noun the daily grind : DRUDGERY, toil, hard work, labour, donkey work, exertion, chores, slog; informal fag, sweat; poetic/literary travail.
25A0; grind away LABOUR, toil, work hard, slave (away), work one's fingers to the bone, work like a Trojan, work like a dog; informal slog, plug away, beaver away, work one's socks off; Brit. informal graft; poetic/literary travail; archaic drudge.
25A0; grind someone down OPPRESS, crush, persecute, tyrannize, ill-treat, maltreat.