crack (v.) Look up crack at Dictionary.com
Old English cracian "make a sharp noise," from Proto-Germanic *krakojan (cognates: Middle Dutch craken, Dutch kraken, German krachen), probably imitative. Related: Cracked; cracking. From early 14c. as "to utter, say, speak, talk," especially "speak loudly or boastingly" (late 14c.). To crack a smile is from 1835, American English; to crack the whip in the figurative sense is from 1886.
crack (n.) Look up crack at Dictionary.com
"a split, an opening," mid-15c., earlier "a splitting sound; a fart; the sound of a trumpet" (late 14c.), probably from crack (v.). 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 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" (as in a crack shot) is slang from 1793, perhaps from earlier verbal sense of "do any thing with quickness or smartness" (Johnson). Grose (1796) has "THE CRACK, or ALL THE CRACK. The fashionable theme, the go." To fall through the cracks figuratively, "escape notice," is by 1975.