Old English. Originally cognate with or formed similarly to Middle Dutch inlichten, Middle Low German inlüchten, Old High German inliuhten, Gothic inliuhtjan from the Germanic base of in- + the Germanic base of light, probably after classical Latin illūmināre illuminate. In later use probably merged with a later formation from en- + light, or perhaps reanalysed as showing en- and light. Compare onlight, alight.