Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “illusion”

illusion

noun uk   /ɪˈluː.ʒən/ us  
C2 [C or U] an idea or belief that is not true: He had no illusions about his talents as a singer. I'm under no illusions (= I understand the truth) about the man I married. My boss is labouring under the illusion that (= wrongly believes that) the project will be completed on time. C2 [C] something that is not really what it seems to be: A large mirror in a room can create the illusion of space. The impression of calm in the office is just an illusion.
(Definition of illusion from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of illusion?
Browse related topics

You are looking at an entry to do with Hiding and disguising, but you might be interested in these topics from the Showing and hiding topic area:

Add Cambridge dictionaries to your browser to your website

Definitions of “illusion” in other dictionaries

Word of the Day

hello stranger

said to a person that you know but have not seen for a long time

Word of the Day

Come on – you can do it! Phrasal verbs with ‘come’.

by Liz Walter​,
November 19, 2014
As part of an occasional series on the tricky subject of phrasal verbs, this blog looks at ones formed with the verb ‘come’. If you are reading this blog, I’m sure you already know come from, as it is one of the first things you learn in class: I come from Scotland/Spain.

Read More 

silver splicer noun

November 17, 2014
informal a person who marries in later life Newly retired and now newlywed – rise of the ‘silver splicers’ Reaching pension age becomes a trigger to tie the knot as baby-boomers begin to redefine retirement

Read More