rock

{{11}}rock (n.) "stone," O.E. rocc (in stanrocc "stone rock or obelisk"), also from O.N.Fr. roque, from M.L. rocca (767), from V.L. *rocca, of uncertain origin, sometimes said to be from Celtic (Cf. Bret. roch). It seems to have been used in Middle English principally for rock formations as opposed to individual stones. Meaning "precious stone, especially a diamond," is 1908, U.S. slang. Figurative use for "sure foundation" (especially with reference to Christ) is from 1520s. Meaning "crystalized cocaine" is attested from 1973, in West Coast U.S. slang. Rock-bottom "lowest possible" is from 1856. Rock-salt is from 1707. Rock-ribbed is from 1776, originally of land; figurative sense of "resolute" first recorded 1887. 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]

{{12}}rock (v.¹) "to sway," late O.E. roccian, related to O.N. rykkja "to pull, tear, move," Swed. rycka "to pull, pluck," M.Du. rucken, O.H.G. rucchan, Ger. rücken "to move jerkily." For musical senses, see ROCK (Cf. rock) (v.²). Rocking horse is first recorded 1724; rocking chair is from 1766. To rock the boat in the figurative sense "stir up trouble" is from 1914. Rock-a-bye first recorded 1805 in nursery rhyme.

{{12}}rock (v.²) "to dance to popular music with a strong beat," 1948 (first attested in song title "We're gonna rock"), from ROCK (Cf. rock) (v.¹), in earlier blues slang sense of "to cause to move with musical rhythm" (1922); often used at first with sexual overtones (Cf. 1922 song title "My Man Rocks Me (with One Steady Roll)"). Sense developed early 1950s to "play or dance to rock and roll music." Noun sense of "musical rhythm characterized by a strong beat" is from 1946, in blues slang. Rock star attested by 1966. Rocksteady, Jamaican pop music style (precursor of reggae), is attested from 1969.