What is the X in X-mas?
Old English grindan "to rub together, grate, scrape," forgrindan "destroy by crushing" (class III strong verb; past tense grand, past participle grunden), from Proto-Germanic *grindanan (cf. Dutch grenden), related to ground, from PIE *ghrendh- "to grind" (cf. Latin frendere "to gnash the teeth," Greek khondros "corn, grain," Lithuanian grendu "to scrape, scratch"). Meaning "to make smooth or sharp by friction" is from c.1300. Most other Germanic languages use a verb cognate with Latin molere (cf. Dutch malen, Old Norse mala, German mahlen).
late 12c., "gnashing the teeth," from grind (v.). The sense "steady, hard work" first recorded 1851 in college student slang (but cf. gerund-grinder, 1710); the meaning "hard-working student" is American English slang from 1864.
bump and grind, if you can't find 'em
1. (MIT and Berkeley) To prettify hardcopy of code, especially LISP code, by reindenting lines, printing keywords and comments in distinct fonts (if available), etc. This usage was associated with the MacLISP community and is now rare; prettyprint was and is the generic term for such operations.
2. (Unix) To generate the formatted version of a document from the nroff, troff, TeX, or Scribe source.
3. To run seemingly interminably, especially (but not necessarily) if performing some tedious and inherently useless task. Similar to crunch or grovel. Grinding has a connotation of using a lot of CPU time, but it is possible to grind a disk, network, etc.
See also hog.
4. To make the whole system slow. "Troff really grinds a PDP-11."
5. "grind grind" excl. Roughly, "Isn't the machine slow today!"
(Ex. 32:20; Deut. 9:21; Judg. 16:21), to crush small (Heb. tahan); to oppress the poor (Isa. 3:5). The hand-mill was early used by the Hebrews (Num. 11:8). It consisted of two stones, the upper (Deut. 24:6; 2 Sam. 11:21) being movable and slightly concave, the lower being stationary. The grinders mentioned Eccl. 12:3 are the teeth. (See MILL.)