O.E. cracian "make a sharp noise," from P.Gmc. *krakojan, probably onomatopoeic. The noun meaning "split, opening," is 14c. Meaning "try, attempt" first attested 1836, probably a hunting metaphor, from slang sense of "fire a gun." Meaning "rock cocaine" is first attested 1985. Cracked "mentally unsound" is 17c. (though the equivalent Gk. word was used in this sense by Aristophanes), while crack as in "top-notch, superior" is slang from 1793. Crackpot "pretentious, worthless person" dates from 1883. The superstition that it is bad luck to step on sidewalk cracks has been traced to c.1890.
The deep crease between the buttocks (unknown date, but very old)
(also crack cocaine) Cocaine freebase, a very pure crystalline cocaine intended for smoking rather than inhalation; coke: Crack's low price and quick payoff make it especially alluring to teenagers(1985+ Narcotics)