Etymology
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crack (v.)

Old English cracian "make a sharp noise, give forth a loud, abrupt sound," from Proto-Germanic *krakojan (source also of Middle Dutch craken, Dutch kraken, German krachen); the whole group is probably ultimately imitative. Related: Cracked; cracking.

From c. 1300 as "to burst, split open" (intransitive), also transitive, "to cause to break into chinks." From 1785 as "break or crush into small pieces." Of the voice, "change tone suddenly," as that of a youth passing into manhood, c. 1600. Meaning "to open and drink" (a bottle) is from 16c.

From early 14c. as "to utter, say, speak, talk freely," especially "speak loudly or boastingly" (late 14c.). To crack a smile is from 1835, American English; to crack a joke is by 1732, probably from the "speak, say" sense. To crack the whip in the figurative sense is from 1886. Get cracking "go to work, start doing what is to be done" is by 1937.

What is a crack in English? A chat! The synonym is as perfect as possible; yet the words are subtly distinguished by a whole hemisphere of feeling. A chat, by comparison "wi' a crack," is a poor, frivolous, shallow, altogether heartless business. A crack is, indeed, only adequately to be defined as a chat with a good, kindly, human heart in it .... [P.P. Alexander, notes to "Last Leaves," Edinburgh, 1869]
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crack (n.)

"a split, an opening, narrow fracture," mid-15c., earlier "a splitting sound; a fart; the sound of a trumpet" (late 14c.), probably from crack (v.).

Meaning "sharp, resounding blow" is from 1836. Meaning "rock cocaine" is first attested 1985. The superstition that it is bad luck to step on sidewalk cracks has been traced to c. 1890. Meaning "try, attempt" first attested 1830, nautical, probably a hunting metaphor, from slang sense of "fire a gun."

At their head, apart from the rest, was a black bull, who appeared to be their leader; he came roaring along, his tail straight an [sic] end, and at times tossing up the earth with his horns. I never felt such a desire to have a crack at any thing in all my life. He drew nigh the place where I was standing; I raised my beautiful Betsey to my shoulder, took deliberate aim, blazed away, and he roared, and suddenly stopped. ["A Narrative of the Life of David Crockett, Written by Himself," Philadelphia, 1834]

Adjectival meaning "top-notch, superior, excellent, first rate" (as in a crack shot) is slang from 1793, perhaps from earlier verbal sense of "do any thing with quickness or smartness" [Johnson], or from the verb in the sense of "speak boastingly" and suggesting "having qualities to be proud of" [Century Dictionary]. Grose (1796) has "THE CRACK, or ALL THE CRACK. The fashionable theme, the go." To fall or slip through the cracks figuratively, "escape notice," is by 1975. Crack-brained "demented" is attested from 1630s. The biblical crack of doom is in reference to the sound (Old English translates it as swegdynna maest).

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crack-up (n.)

1926, in reference to airplane crashes; 1936, "disintegration under stress, mental collapse" [Fitzgerald]; from the verbal phrase, from crack (v.) + up (adv.). The verbal phrase in the meaning "to break up laughing" is by 1967, transitive and intransitive. Its earliest sense was "to praise extravagantly" (as in not all it's cracked up to be).

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cracking (adj.)

"excellent, first-rate," 1830s, colloquial, present-participle adjective from crack (v.).

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safecracker (n.)

also safe-cracker, 1897, from safe (n.) + agent noun from crack (v.). Originally in reference to thieves who used dynamite.

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crackhead (n.)

"crack cocaine addict," slang, by 1986, from crack (n.) in the drug slang sense + head (n.). In earlier slang, crack-headed meant "crazy" (1796), from the literal sense of crack.

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cracked (adj.)

mid-15c., "broken by a sharp blow," past-participle adjective from crack (v.). From 1560s as "burst, split." Meaning "mentally unsound" is by 1690s. (compare crack-brain "crazy fellow"). The equivalent Greek word was used in this sense by Aristophanes.

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crackle (v.)

"make frequent or rapid cracking noises," mid-15c., crackelen, frequentative of cracken "to crack" (see crack (v.)). Related: Crackled; crackling. The noun, in the sense of "a crackling noise," is recorded from 1833.

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crackpot (n.)

"mentally unbalanced person," 1898, probably from crack (v.) + pot (n.1) in a slang sense of "head." Compare crack-brain "crazy fellow" (late 16c.). Earlier it was used in a slang sense "a small-time big-shot" (1883), and by medical doctors in reference to a "metallic chinking sometimes heard when percussion is made over a cavity which communicates with a bronchus."

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croak (v.)

early 14c., crouken, of birds (crow, raven, crane), "make a low, hoarse sound," imitative or related to Old English cracian (see crack (v.)). Of frogs, c. 1400. Meaning "forebode evil, complain, grumble" is from mid-15c., perhaps from the raven as a bird of foreboding. Slang meaning "to die" is first recorded 1812, from sound of death rattle. Related: Croaked; croaking.

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