jocose adj.

1660s, joque, "a jest, something done to excite laughter," from Latin iocus "joke, jest, sport, pastime" (source also of French jeu, Spanish juego, Portuguese jogo, Italian gioco), from Proto-Italic *joko-, from PIE *iok-o- "word, utterance," from root *yek- (1) "to speak" (cognates: Welsh iaith, Breton iez "language," Middle Irish icht "people;" Old High German jehan, Old Saxon gehan "to say, express, utter;" Old High German jiht, German Beichte "confession").

Originally a colloquial or slang word. Meaning "something not real or to no purpose, someone not to be taken seriously" is from 1791. Black joke is old slang for "smutty song" (1733), from use of that phrase in the refrain of a then-popular song as a euphemism for "the monosyllable." Lithuanian juokas "laugh, laughter," in plural "joke(s)" probably is borrowed from German.

late 14c., "pleasing, gracious; joyful," from Old French jocond or directly from Late Latin iocundus (source of Spanish jocunde, Italian giocondo), variant (influenced by iocus "joke") of Latin iucundus "pleasant, agreeable," originally "helpful," contraction of *iuvicundus, from iuvare "to please, benefit, help, give strength, support," which is from a PIE source perhaps related to the root of iuvenis "young person" (see young (adj.)).

In jocose cheerfulness or light-heartedness is an accidental thing; in jocund it is the essential idea. [Century Dictionary]

"merriment, waggery, mirthfulness," 1640s; see jocose + -ity.