Your English: Collocations: illusion

An illusion is defined as a false belief or idea, or an effect that is different from what is real. 

The latter meaning can apply to various illusions that relate to the senses, these being auditory, optical, perceptual, sensory or visual, as in ‘People have always been intrigued by optical illusions such as stairs that appear to be leading both up and down at the same time’. 

Illusions are by their very nature false, as in ‘Don’t be under any false illusions. This is going to be hard work!’ In the belief that things are better or will be better than they actually are, illusions can be grand or romantic, as in ‘Fortunately, when they chose life on the farm, they had no romantic illusions’. 

Illusions are created, as in ‘Artists can create an illusion of a three-dimensional image on a two-dimensional surface’ and people entertain, harbour, labour under or are under various illusions, as in ‘I harbour no illusions about the complexity of the task ahead’ or ‘She’s under the illusion that she can simply ask for her money back if something goes wrong’. 

Of course, it may be in the interests of some people or groups to maintain, perpetuate, preserve or sustain illusions, as in ‘The government is doing everything to perpetuate the illusion that the opposition caused the financial crash’. 

In the end, however, illusions are often destroyed or shattered and our hopes end in crushing disappointment, as in ‘The defeat shattered any illusions that City fans might harbour that they would retain their grip on the league title’.