apperceive (v.)

c. 1300, "to perceive, notice," especially of internal observation (a sense now obsolete), from Old French apercevoir "perceive, notice, become aware of" (11c.), from Latin ad "to" (see ad-) + percipere "gather, seize entirely," also, figuratively, "to grasp with the mind, learn, comprehend" (see perceive. In modern psychological use (1876), a back-formation from apperception (q.v.). Related: Apperceived; apperceiving; apperceptive.