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between a rock and a hard place

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 from 1976; from 1968 as paper-stone-scissors. A 1967 source says it is based on Japanese Jan Ken Pon (or Janken for short), which is said to mean the same thing more or less.

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.

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 (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.” Related: Rocked; rocking. Rocksteady, Jamaican pop music style (precursor of reggae), is attested from 1969.

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.

American gynecologist and obstetrician who helped develop the first effective oral contraceptive in 1954.

A relatively hard, naturally occurring mineral material. Rock can consist of a single mineral or of several minerals that are either tightly compacted or held together by a cementlike mineral matrix. The three main types of rock are igneous, sedimentary, and metamorphic.
A piece of such material; a stone.

Faced with two equally dangerous or difficult choices or circumstances: “Trying to please two supervisors is like being between a rock and a hard place.” This phrase dates from the early twentieth century.

Also, between the devil and the deep blue sea or Scylla and Charybdis. Between two equally difficult or unacceptable choices. For example, Trying to please both my boss and his supervisor puts me between a rock and a hard place. The rock and hard place version is the newest of these synonymous phrases, dating from the early 1900s, and alludes to being caught or crushed between two rocks. The oldest is Scylla and Charybdis, which in Homer’s Odyssey signified a monster on a rock (Scylla) and a fatal whirlpool (Charybdis), between which Odysseus had to sail through a narrow passage. It was used figuratively by the Roman writer Virgil and many writers since. The devil in devil and deep blue sea, according to lexicographer Charles Earle Funk, referred to a seam around a ship’s hull near the waterline, which, if a sailor was trying to caulk it in heavy seas, would cause him to fall overboard. Others disagree, however, and believe the phrase simply alludes to a choice between hellfire with the devil and drowning in deep waters.

In addition to the idioms beginning with rock

rock bottom
rocks in one’s head, have
rock the boat

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