(1):
(n.) The faculty of perceiving; the faculty, or peculiar part, of man's constitution by which he has knowledge through the medium or instrumentality of the bodily organs; the act of apperhending material objects or qualities through the senses; - distinguished from conception.
(2):
(n.) The quality, state, or capability, of being affected by something external; sensation; sensibility.
(3):
(n.) An idea; a notion.
(4):
(n.) The act of perceiving; cognizance by the senses or intellect; apperhension by the bodily organs, or by the mind, of what is presented to them; discernment; apperhension; cognition.