‘Allusion’ and ‘illusion’ are fairly rare words. They also sound similar, so it is easy to get them mixed up if you’ve never seen them written down. But these terms have very different meanings, so make sure your work is error free by checking out our guide to how they should be used.
Allusion (Indirect Reference)
An ‘allusion’ is an indirect reference to something. For example, the title of David Foster Wallace’s novel Infinite Jest is taken from a line in Hamlet. This is an ‘allusion’ to Shakespeare – rather than a direct reference – because Wallace does not mention Shakespeare or Hamlet in the novel.
And while ‘allusion’ is a noun, the verb form of this word is ‘allude’:
The title of the novel alludes to Act 5, Scene 1 of Hamlet.
As with the noun form above, the key here is that the novel makes an indirect reference to Hamlet. It does not, however, draw attentions to this.
Illusion (Mistaken Perception or Belief)
The word ‘illusion’ usually refers to a mistaken sense perception, such as a mirage. For example, we might say:
I saw the hazy outline of an oasis, but I knew it was an illusion.
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This idea of seeing or sensing something that isn’t really there is also why we call magic tricks ‘illusions’, as well as why trick images are called optical illusions. But we can also use ‘illusion’ to describe a false belief:
I was labouring under an illusion to think I could run a marathon.
Here, ‘labouring under an illusion’ means the speaker was acting on the basis of a mistaken belief (i.e. their ability to run a marathon).
Summary: Allusion or Illusion
Although these words have many letters in common, they have very different meanings. Keep the following definitions in mind:
- An allusion is an indirect reference to something.
- An illusion is a mistaken sense perception or belief.
One trick to remembering this difference is the phrase ‘Staring at optical illusions will make you ill.’ And if you’d like more help with the spelling in your writing, you can always ask a proofreader.