early 15c., "to trick, deceive; treat with scorn or mockery," from Latin illudere "to make sport of, scoff at, mock, jeer at," from assimilated form of in- "in, into" (from PIE root *en "in") + ludere "to play" (see ludicrous).
illocution
illocutionary
illogical
illth
ill-timed
illude
illume
illuminate
illuminati
illumination
illumine