Synesthesia is a condition that happens when a sense, such as sight, triggers another sense, like smell, at the same time. For someone with synesthesia, each letter of the alphabet might have a different odor. Cool!
Synesthesia happens when someone’s senses are blended. The word synesthesia comes from the Greek syn for “together” and the root aisthe for “to feel.” People with synesthesia often don’t realize at first that they have it — they think everyone sees the number 8 as red, for example! The writer Vladimir Nabokov writes about having synesthesia in his memoir Speak, Memory. Synesthesia is another way of perceiving the world, but it’s not a disease.