"of or pertaining to the act or power of perceiving," 1650s, from Latin percept-, past-participle stem of percipere (see perceive) + -ive. In reference to intelligence from 1860. From mid-15c. as the name of a type of optical instrument or magic glass revealing future events. The older word in the mental sense was perceptible (q.v.); also compare Middle English perceivaunt "observant" (late 14c.), from Old French and Medieval Latin. Related: Perceptively; perceptiveness.