Moon-eye \Moon"-eye`\, n. 1. A eye affected by the moon; also, a disease in the eye of a horse. [1913 Webster] 2. (Zool.) (a) Any species of American fresh-water fishes of the genus {Hyodon}, esp. {Hyodon tergisus} of the Great Lakes and adjacent waters. (b) The cisco. [1913 Webster]