An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) A false sense impression of something actually present.
2) Something that produces a false or misleading impression of reality. → optical illusion.
3) An instance of being deceived.

From O.Fr. illusion "a mocking," from L. illusionem (nom. illusio) "a mocking, irony," from illudere "to mock at," literally "to play with," from in- "at" + ludere "to play," from ludus "a game, play;" PIE base *leid- "to play, jest."

Safmân, literally "wrong thought, ~ idea," from saf "wrong" (Tâleši), → false, + mân "thought," → idea.

A perception of visual stimuli in which what is perceived is in a way different from the way it is in reality. Same as visual illusion.

→ optical; → illusion.