1 a person who does crazy things that are often dangerous:
This lunatic in a white van pulled out right in front of me!
2 (old-fashioned) a person who is severely mentally ill (the use of this word is now offensive):
a dangerous / homicidal lunatic
ORIGIN Originally from the Latin lunaticus (luna = moon), because people believed that the changes in the moon caused temporary madness.
adjective crazy, ridiculous or extremely stupid:
lunatic ideas * a lunatic smile
IDIOMS
the lunatic fringe noun [sing.+sing./pl.v.] (disapproving) those members of a political or other group whose views are considered to be very extreme and crazy:
They stressed that only the lunatic fringe of the movement was involved in the incident.
