/ˈluːnətɪk/
lu·na·tic
BrE /ˈluːnətɪk/
NAmE /ˈluːnətɪk/
a person who does crazy things that are often dangerous
SYN maniac
This lunatic in a white van pulled out right in front of me!
(old-fashioned)
a person who is severely mentally ill (the use of this word is now offensive)
ORIGIN Originally from the Latin lunaticus ( luna = moon), because people believed that the changes in the moon made people go mad temporarily.
lu·na·tic
BrE /ˈluːnətɪk/
NAmE /ˈluːnətɪk/
crazy, ridiculous or extremely stupid
lunatic ideas
a lunatic smile
the ˌlunatic ˈfringe [sing. + sing./pl. v.]
(disapproving)
those members of a political or other group whose views are considered to be very extreme and crazy