LUNATIC. A term derived from the Lat. luna, “moon,” indicating a person under the influence of the moon. This is the meaning of the Gr. verb σεληνιάζεται (Matt 4:24; 17:15), which reflected the Gr. idea, found also in other cultures, that an individual could be affected mentally by the moon. The insanity contemplated was thought to have recurring periods which corresponded to the lunar phases. The verb was used in KJV (Matt 4:24), along with δαιμονι ζομένους, as if to distinguish between the two conditions. The KJV used the term to describe an epileptic boy (Matt 17:15), while the RSV rendered it on both occasions by “epilepsy.” It would thus seem that the usage in KJV (Matt 4:24) was of a popular, untechnical kind. The KJV (Matt 17:15) described a “lunatic” who was epileptic, but the same symptoms were attributed in Mark 9:17 to a “dumb spirit” and in Luke 9:39 to a “spirit.” The word tended to be used inexactly, and while it included epilepsy it did not necessarily exclude possession.