Optical-illusion

noun
1.
See under (def 4).
[ih-loo-zhuh n] /ɪˈlu ʒən/
noun
1.
something that deceives by producing a false or misleading impression of reality.
2.
the state or condition of being deceived; misapprehension.
3.
an instance of being deceived.
4.
Psychology. a perception, as of visual stimuli (optical illusion) that represents what is perceived in a way different from the way it is in reality.
5.
a very thin, delicate tulle of silk or nylon having a cobwebbed appearance, for trimmings, veilings, and the like.
6.
Obsolete. the act of deceiving; deception; delusion.
/ɪˈluːʒən/
noun
1.
a false appearance or deceptive impression of reality: the mirror gives an illusion of depth
2.
a false or misleading perception or belief; delusion: he has the illusion that he is really clever
3.
(psychol) a perception that is not true to reality, having been altered subjectively in some way in the mind of the perceiver See also hallucination
4.
a very fine gauze or tulle used for trimmings, veils, etc
noun
1.
an object causing a false visual impression
2.
an instance of deception by such an object
n.

mid-14c., “act of deception,” from Old French illusion “a mocking, deceit, deception” (12c.), from Latin illusionem (nominative illusio) “a mocking, jesting, irony,” from illudere “mock at,” literally “to play with,” from assimilated form of in- “at, upon” (see in- (2)) + ludere “to play” (see ludicrous). Sense of “deceptive appearance” developed in Church Latin and was attested in English by late 14c. Related: Illusioned “full of illusions” (1920).

illusion il·lu·sion (ĭ-lōō’zhən)
n.

il·lu’sion·al or il·lu’sion·ar’y (-zhə-něr’ē) adj.