joke (n.)youdaoicibaDictYouDict[joke 词源字典]
1660s, joque, "a jest, something done to excite laughter," from Latin iocus "joke, sport, pastime," from PIE root *yek- (1) "to speak" (cognates: Breton iez "language," Old High German jehan "to say," German Beichte "confession").

Originally a colloquial or slang word. Meaning "something or someone not to be taken seriously" is from 1791. Practical joke "trick played on someone for the sake of a laugh at his expense" is from 1804 (earlier handicraft joke, 1741). Black joke is old slang for "smutty song" (1730s), from use of that phrase in the refrain of a then-popular song as a euphemism for "the monosyllable."[joke etymology, joke origin, 英语词源]