something that someone believes that is definitely not true► illusion a belief or idea that is false, especially a belief in something good about yourself or about the situation you are in: · She thought he loved her but it was just an illusion.· Alcohol gives some people the illusion of being witty and confident.illusion that: · There seems to be a widespread illusion that there are no class barriers anymore.under an illusion: · People had bought these houses under the illusion that their value would just keep on rising.
► fallacy something that a lot of people believe but which is completely untrue: · The idea that a good night's sleep will cure everything is a complete fallacy.· It's a fallacy that all fat people are fat simply because they eat too much.
► myth something a lot of people believe because they want to believe it, not because it is based on fact: · The first myth about motherhood is that new mothers instantly fall in love with their babies.· It is a myth that battered women deserve or want to be beaten.
► delusion a completely mistaken idea about yourself or the situation you are in, especially one that everyone else knows is wrong: · She now had to finally forget the dreams and delusions of her youthunder a delusion: · I was still under the delusion that everyone was trying to cheat me.
► mistaken belief a belief you have that is wrong, although you do not realize it is wrong at the time when you have it: · When I started as a teacher I had the mistaken belief that all kids are interested in learning.
► misconception something that is not true but which people believe because they do not have all the facts or they have not properly understood the situation: · No, it's not actually true that rail travel is more expensive - that's a misconception.misconception that: · Employers seem to share the general misconception that young people are more efficient than older workers.
► old wives' tale a popular belief or piece of advice that has existed for a long time but which you think is stupid: · It's not true that if trees have a lot of fruit in the autumn it will be a cold winter - that's just an old wives' tale.