1620s, "disposed to joking," from Latin iocularis "funny, comic," from ioculus "joke," diminutive of iocus "pastime; a joke" (see joke (n.)). Often it implies evasion of an issue by a joke.
jock
jockey
jockstrap
jocose
jocosity
jocular
jocularity
joculator
jocund
jocundity
jod