Word Origin & History
"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). Seems to have been used in M.E. principally for rock formations as opposed to individual stones. Meaning
"precious stone, especially a diamond," is 1908, U.S. slang. Fig. use for "sure foundation" (especially with ref. to Christ) is from 1526. Meaning "crystalized cocaine" is attested from 1973, in West Coast U.S. slang. Rocks "ice cubes" is from 1946; slang meaning "testicles" is first recorded in phrase get (one's) rocks off "achieve intense satisfaction." On the rocks "ruined" is from 1889. Rock-bottom "lowest possible" is from 1856. Rock-salt is from 1707. Between a rock and a hard place first attested 1921, originally in Arizona. Rock-ribbed is from 1776, originally of land; fig. sense of "resolute" first recorded 1887.
"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
(v.2). Rocking horse is first recorded 1724; rocking chair is from 1766.
To rock the boat is attested from 1931. Rock-a-bye first recorded 1805 in nursery rhyme.
"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 (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. Rocksteady, Jamaican pop music style (precursor of reggae), is attested from 1969.