A perceptual phenomenon in which a sense impression relating to one sense is produced by stimulation of another sense. For example, some people see colors in response to tastes or smells, some experience a taste or smell in response to numbers or words, others experience shapes, colors or textures when listening to music. People who report such experiences are known as synesthetes. Synesthesia is often reported by visual artists (Vincent van Gogh, Wassily Kandinsky, David Hockney), musicians (Franz Liszt, Nikolai Rimsky-Korsakov, Duke Ellington) and poets (Charles Baudelaire, Arthur Rimbaud). Web resources here and here.

Wassily Kandinsky (1866–1944).