CALIGATION
n.Darkness; dimness; cloudiness. In medical authors, caligation or caligo, is an opakeness or cloudiness of the anterior surface of the crystaline lens, causing dimness of sight; impaired sight from obstruction to the passage of light, or cataract.
Cal `i *ga "tion, n. Etym: [L. caligatio, fr. caligare to emit vapor, to be dark, from caligo mist, darkness. ]