U.S. slang; said in "Dictionary of American Slang" to be originally 1920s army and 1930s college student slang for "venereal disease." Thus by 1940, "dirty, disreputable person," and by 1950, "undesirable impurity." By 1945 (with various modifiers) it was the G.I.'s name for disease of any and every sort." 

Perhaps this word is a continuation of crud as the old metathesis variant of curd (q.v.), which would make it an unconscious return to the original Middle English form of that word. Century Dictionary (1897) has crud only in the sense "Obsolete or dialectal form of curd."

"action of talking," earlier "chatter, loquacity, idle talk" (mid-13c.), also "falsehood, deceit," originally "a gibe, a taunt" (c. 1200), mid-13c., probably from a Scandinavian source akin to Old Norse gabb "mocking, mockery," and in part from Old French gap, gab "joke, jest; bragging talk," which also is probably from Scandinavian (compare gab (v.)). Probably also there is influence from Scottish and northern English gab "the mouth" (see gob (n.2)); OED reports the word "Not in dignified use." Gift of (the) gab "talent for speaking" is from 1680s.

"risk something of value on a game of chance," 1726 (implied in gambling), from a dialectal survival of Middle English gammlen, variant of gamenen "to play, jest, be merry," from Old English gamenian "to play, joke, pun," from gamen (see game (n.)), with form as in fumble, etc. Or possibly gamble is from a derivative of gamel "to play games" (1590s), itself likely a frequentative from game. Originally regarded as a slang word. The unetymological -b- may be from confusion with unrelated gambol (v.). Transitive meaning "to squander in gambling" is from 1808. Related: Gambled; gambling.

elder son of Adam and Eve, the first murderer and the first fratricide, from Hebrew Qayin, literally "created one," also "smith," from Semitic stem q-y-n "to form, to fashion." Figurative use for "murderer, fratricide" is from late 14c. The Cainites were a 2c. heretical sect who revered Cain, Judas, and other wicked characters in Scripture.

To raise Cain "behave disruptively" is recorded from 1840, American English.

Why are Adam and Eve the oldest sugar planters? Because they were he first to raise Cain. [joke in The Monthly Traveller, Boston, July 1832, and elsewhere]

The surnames McCain, McCann, etc., are a contraction of Irish Mac Cathan "son of Cathan," from Celtic cathan, literally "warrior," from cath "battle."

late 14c., jupartie , ioparde, etc., "danger, risk;" earlier "a cunning plan, a stratagem" (c. 1300), from or based on Old French jeu parti "a lost game," more correctly "a divided game, game with even chances" (hence "uncertainty"). The sense perhaps developed in Anglo-French.

This is from jeu "a game" (from Latin iocus "jest;" see joke (n.)) + parti, past participle of partir "to divide, separate" (10c.), from Latin partire/partiri "to share, part, distribute, divide," from pars "a part, piece, a share" (from PIE root *pere- (2) "to grant, allot"). Jeopardous "in peril" (mid-15c.) is now obsolete.

c. 1400, "to desecrate, profane;" mid-15c., "to make foul or dirty," also "to rape, deflower," alteration of earlier defoulen, from Old French defouler "trample down, violate," also "ill-treat, dishonor," from de- "down" (see de-) + foler "to tread," from Latin fullo "person who cleans and thickens cloth by stamping on it" (see foil (v.1)).

The alteration (or re-formation) in English is from influence of Middle English filen (v.) "to render foul; make unclean or impure," literal and figurative, from Old English fylen (trans.), related to Old English fulian (intrans.) "to become foul, rot," from the source of foul (adj.). Compare befoul, which also had a parallel form befilen. Related: Defiled; defiling.

"to dance in a way that simulates the body's action in copulation," by 2005, alteration of twurk, which seems to have originated in the Atlanta, Georgia, strip club and hip-hop scene and first came to wide attention in the Ying Yang Twins' 2000 song "Whistle While You Twurk," described as "an ode to strippers" ["Country Fried Soul, Adventures in Dirty South Hip-Hop"]. Probably ultimately imitative of something. Related: Twerked; twerking. There is a verb twirk from 1599, "to pull, tug, twirl," what a man does with his mustache, but OED regards this as possibly a misprint of twirl.

early 15c., smateren, intransitive, "talk idly, chatter; talk ignorantly or superficially," a word of uncertain origin, perhaps imitative. Similar words are found in Middle High German smetern "to chatter" and Swedish smattra "to patter, rattle," and compare Danish snaddre "chatter, jabber," Dutch snateren, German schnattern "cackle, chatter, prattle."

Or it might be a special sense of Middle English smateren "to make dirty, defile" (late 14c.). Middle English Compendium compares bismotered "bespattered," smotten "corrupt, debase, defile."

The older sense is obsolete. The meaning "have slight or superficial knowledge of, be a smatterer," is by 1520s. Related: Smattered; smattering.

1610s, "pertaining to play or sport" (a sense now obsolete), from Latin ludicrus "sportive" (source of Old French ludicre), from ludicrum "amusement, game, toy, source of amusement, joke," from ludere "to play."

This verb, along with Latin ludus "a game, play," is from the PIE root *leid- or *loid- "to play," perhaps literally "to let go frequently" [de Vaan], which is the source also of Middle Irish laidid "impels;" Greek lindesthai "to contend," lizei "plays;" Albanian lind "gives birth," lindet "is born;" Old Lithuanian leidmi "I let," Lithuanian leisti "to let," laidyti "to throw," Latvian laist "let, publish, set in motion."

Sense of "ridiculous, apt to evoke ridicule or jest" is attested from 1782. Related: Ludicrously; ludicrousness.

1801, "spectre, apparition, ghost," from Dutch spook, from Middle Dutch spooc "spook, ghost," from a common Germanic source (German Spuk "ghost, apparition," Middle Low German spok "spook," Swedish spok "scarecrow," Norwegian spjok "ghost, specter," Danish spøg "joke"), of unknown origin. According to Klein's sources, possible outside connections include Lettish spigana "dragon, witch," spiganis "will o' the wisp," Lithuanian spingu, spingėti "to shine," Old Prussian spanksti "spark."

Meaning "undercover agent" is attested from 1942. The derogatory racial sense of "black person" is attested from 1940s, perhaps from notion of dark skin being difficult to see at night. Black pilots trained at Tuskegee Institute during World War II called themselves the Spookwaffe.