synaesthesia (n.) Look up synaesthesia at Dictionary.com
also synesthesia, "sensation in one part of the body produced by stimulus in another," 1881, in some cases via French, from Modern Latin, from Greek syn- "together" (see syn-) + aisthe "to feel, perceive," related to aisthesis "feeling," from PIE root *au- "to perceive" (see audience) + abstract noun ending -ia. Also psychologically, of the senses (colors that seem to the perceiver to having odor, etc.), from 1891. Related: Synaesthetic (adj.).