rock (n.1)

"stone, mass of mineral matter," c. 1300, from Old English rocc (as in stanrocc "stone rock or obelisk") and directly from Old North French roque, which is cognate with Medieval Latin rocca (8c.), from Vulgar Latin *rocca, of uncertain origin, according to Klein sometimes said to be from Celtic (compare Breton roch).

In Middle English it seems to have been used principally for rock formations as opposed to individual stones. Meaning "precious stone, especially a diamond," is 1908, U.S. slang. Meaning "crystallized cocaine" is attested from 1973, in West Coast U.S. slang. Figurative use for "sure foundation" (especially with reference to Christ) is from 1520s; but also from 1520s as "source of danger or destruction," in reference to shipwrecks (as in on the rocks). Also used attributively in names of animals that frequent rocky habitats, as in rock lobster (1843). Between a rock and a hard place first attested 1921:

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]

Rock-ribbed is from 1776, originally of land; figurative sense of "resolute" first recorded 1887. Rock-happy (1945) was U.S. Pacific Theater armed forces slang for "mentally unhinged after too much time on one island."

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.

rock (v.1)

"to sway," late Old English roccian "move a child gently to and fro," related to Old Norse rykkja "to pull, tear, move," Swedish rycka "to pull, pluck," Middle Dutch rucken, Old High German rucchan, German rücken "to move jerkily."

Meaning "cause to sway back and forth" is from late 13c. Intransitive sense from late 14c. For popular music senses, see rock (v.2). Related: Rocked; rocking. To rock the boat in the figurative sense "stir up trouble" is from 1914. Rock-a-bye first recorded 1805 in nursery rhyme.

rock (v.2)

"to dance to popular music with a strong beat," 1948 (first attested in song title "We're gonna rock"), from rock (v.1), in earlier blues slang sense of "to cause to move with musical rhythm" (1922); often used at first with sexual overtones (as in 1922 song title "My Man Rocks Me (with One Steady Roll)"). Sense developed early 1950s to "play or dance to rock and roll music." Related: Rocked; rocking. Rocksteady, Jamaican pop music style (precursor of reggae), is attested from 1969.

rock (n.2)

"action of rocking; a movement to and fro," 1823, from rock (v.1). As short for rock and roll, by 1957; but sense of "musical rhythm characterized by a strong beat" is from 1946, in blues slang. Rock star attested by 1966.

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Definitions of rock from WordNet
rock (n.)
a lump or mass of hard consolidated mineral matter;
he threw a rock at me
Synonyms: stone
rock (n.)
material consisting of the aggregate of minerals like those making up the Earth's crust;
that mountain is solid rock
Synonyms: stone
rock (n.)
(figurative) someone who is strong and stable and dependable; "Thou art Peter, and upon this rock I will build my church"--Gospel According to Matthew;
he was her rock during the crisis
rock (n.)
hard bright-colored stick candy (typically flavored with peppermint);
Synonyms: rock candy
rock (n.)
a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western;
rock is a generic term for the range of styles that evolved out of rock'n'roll.
Synonyms: rock 'n' roll / rock'n'roll / rock-and-roll / rock and roll / rock music
rock (n.)
pitching dangerously to one side;
Synonyms: careen / sway / tilt
rock (v.)
move back and forth or sideways;
She rocked back and forth on her feet
the ship was rocking
Synonyms: sway / shake
rock (v.)
cause to move back and forth;
rock the cradle
rock the baby
Synonyms: sway
Rock (n.)
United States gynecologist and devout Catholic who conducted the first clinical trials of the oral contraceptive pill (1890-1984);
Synonyms: John Rock