Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

Medical Dictionary

illusion

play
noun il·lu·sion \il-ˈü-zhən\

Medical Definition of illusion

  1. 1:  a misleading image presented as a visual stimulus

  2. 2a:  perception of something objectively existing in such a way as to cause misinterpretation of its actual nature; especially :  optical illusion—compare delusion 2b:  hallucination 1c:  a pattern capable of reversible perspective

illusional \-ˈüzh-nəl, -ən-əl\play adjective




Seen and Heard

What made you want to look up illusion? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

to work hard

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image567572573

Which of these is a synonym of unctuous?

oily prompt angry maudlin
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ