King James Bible Dictionary

Probably the same as epileptic, the symptoms of which disease were supposed to be more aggravated as the moon increased. In Matthew 4:24 "lunatics" are distinguished from demoniacs. In 17:15 the name "lunatic" is applied to one who is declared to have been possessed. (See DAEMONIAC.)

LU'NATIC, adjective Affected by a species of madness, supposed to be influenced by the moon.

LU'NATIC, noun A person affected by insanity, supposed to be influenced or produced by the moon, or by its position in its orbit; a madman.

(from the Latin Luna , the moon, because insane persons, especially those who had lucid intervals, were once supposed to be affected by the changes of the moon). This word is used twice in the New Testament

(Matthew 4:24; 17:15) Translated epileptic in the Revised Version.) It is evident that the word itself refers to same disease affecting both the body and the mind, which might or might not be a sign of possession By the description of (Mark 9:17-26) it is concluded that this disease was epilepsy.