synaesthesia, defined

syn·es·the·sia also syn·aes·the·sia ( P ) Pronunciation Key (sns-thzh)
n.

1. A condition in which one type of stimulation evokes the sensation of another, as when the hearing of a sound produces the visualization of a color.
2. A sensation felt in one part of the body as a result of stimulus applied to another, as in referred pain.
3. The description of one kind of sense impression by using words that normally describe another.