Synesthesia
"The concurrent response of two or more of the senses to the stimulation of one" (Harmon). It also means the mixing of two or more senses at one time. Synesthesia is usually used in Poetry
Functions of Synesthesia
Writers tend to use this to give their writing more meaning. It gives writers the extra boost of creativity and description. Synesthesia makes writing more interesting and appealing to an audience.