late 14c. (O.E. had inlihtan), "to remove the dimness or blindness (usually figurative) from one's eyes or heart," from en- + lighten. Related: Enlightened; enlightening.
unenlightened
1662, "not lit up," from un- (1) "not" + pp. of enlighten. Meaning "not mentally illuminated" is attested from c.1656.