What is the meaning of Lunatic?

An insane person.

Crazed, mad, insane, demented.

Relating to the Moon; lunar.

Influenced or affected by the Moon.

somnambulist, sleepwalker

dullard, fool, scatterbrain

born in the same month as another

having hallucinations

fantastic, unreal, bizarre

having unusual or strange ideas and behavior

fearful

Source: wiktionary.org