rock-face (n.)

[stone, mass of mineral matter], Middle English rokke, roche "stone as a substance; large rocky formation, rocky height or outcrop, crag," from Old English rocc (as in stanrocc "stone rock or obelisk") and directly from Old North French roque, variant of Old French roche, which is cognate with Medieval Latin rocca (8c.), from Vulgar Latin *rocca, a word of uncertain origin. According to Klein and Century Dictionary, sometimes said to be from Celtic (compare Breton roch). Diez suggests Vulgar Latin *rupica, from Latin rupes "rocks."

In Middle English it seems to have been used principally for large rock formations but occasionally of individual boulders. The extended sense of "a stone of any size" is by 1793, American English colloquial, and long was considered incorrect.

It is an error to use rock for a stone so small that a man can handle it : only a fabulous person or a demi-god can lift a rock. [Century Dictionary]

The meaning "precious stone," especially a diamond, is by 1908, U.S. slang; the sense of "crystallized cocaine" is attested from 1973 in West Coast slang. Also used attributively in names of animals that frequent rocky habitats, as in rockfish, rock badger, rock lobster (the last attested by 1843).

Rock is used figuratively for "a sure foundation, something which gives one protection and security" (especially with reference to Christ), from the 1520s (Tyndale); but it also has been used since the 1520s as "cause or source of peril or destruction," an image from shipwrecks.

Between a rock and a hard place "beset by difficulties with no good alternatives" is attested by 1914 in U.S. Southwest:

to be between a rock and a hard place, vb. ph. To be bankrupt. Common in Arizona in recent panics; sporadic in California. [Dialect Notes, vol. v, part iv, 1921]

As an example of fine distinctions, a party of men were discussing the present situation of the German army, this week. One remarked that the Germans were between the devil and the deep sea; while another corrected him by saying that the Germans were between the upper and nether mill stone. The third man whose name is Pilgreen, and who works in the treasurer's office, simply remarked that the Germans were between a rock and a hard place. [local item in the Pouteau (Oklahoma) Weekly Sun,  Oct. 1, 1914]

The rock-scissors-paper game is attested by that name by 1976 (as paper stone and scissors by 1941). Sources agree it is based on Japanese Jan Ken Po or Jan Ken Pon (or Janken for short); the Japanese game is described in English publications by 1879.

c. 1300, "the human face, a face; facial appearance or expression; likeness, image," from Old French face "face, countenance, look, appearance" (12c.), from Vulgar Latin *facia (source also of Italian faccia), from Latin facies "appearance, form, figure," and secondarily "visage, countenance," which probably is literally "form imposed on something" and related to facere "to make" (from PIE root *dhe- "to set, put").

Replaced Old English andwlita "face, countenance" (from root of wlitan "to see, look") and ansyn, ansien, the usual word (from the root of seon "see"). Words for "face" in Indo-European commonly are based on the notion of "appearance, look," and are mostly derivatives from verbs for "to see, look" (as with the Old English words, Greek prosopon, literally "toward-look," Lithuanian veidas, from root *weid- "to see," etc.). But in some cases, as here, the word for "face" means "form, shape." In French, the use of face for "front of the head" was given up 17c. and replaced by visage (older vis), from Latin visus "sight."

From late 14c. as "outward appearance (as contrasted to some other reality);" also from late 14c. as "forward part or front of anything;" also "surface (of the earth or sea), extent (of a city)." Typographical sense of "part of the type which forms the letter" is from 1680s.

Whan she cometh hoom, she raumpeth in my face And crieth 'false coward.' [Chaucer, "Monk's Tale"]

Face to face is from mid-14c. Face time is attested from 1990. To lose face "lose prestige" (1835), is from Chinese tu lien; hence also save face (1915). To show (one's) face "make or put in an appearance" is from mid-14c. (shewen the face). To make a face "change the appearance of the face in disgust, mockery, etc." is from 1560s. Two faces under one hood as a figure of duplicity is attested from mid-15c.

Two fases in a hode is neuer to tryst. ["Awake lordes," 1460]