Main Entry: syn·es·the·sia

Pronunciation: \ˌsi-nəs-ˈthē-zh(ē-)ə\

Function: noun

Etymology: New Latin, from syn- + -esthesia (as in anesthesia)

Date: circa 1891

1 : a concomitant sensation; especially : a subjective sensation or image of a sense (as of color) other than the one (as of sound) being stimulated
2 : the condition marked by the experience of such sensations

— syn·es·thet·ic \-ˈthe-tik\ adjective