Illusion
Definition 1 of 4
Pro Tip 1/2
Not Real
Remember 'illusion' suggests something seems real but isn't, often due to circumstances. The shadows on the wall created the illusion of movement.
Pro Tip 2/2
Visual Deception
An 'illusion' can be a visual trick that confuses the eyes and brain. The lines seem curved, but it's just an optical illusion.