Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.

WORD ORIGIN

1590s, from French illusorie, from Late Latin illusorius "ironical, of a mocking character," from illus-, past participle stem of Latin illudere "mock at," literally "to play with," from assimilated form of in- "at, upon" (see in- (2)) + ludere "to play" (see ludicrous).

Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.