nutcase

/ˈnʌtkeɪs/

noun

Meaning

An eccentric or odd person.
Someone who is insane.

Synonyms

kook,

nutbag,

nutter,

odd duck,

wacko,

weirdo,

crackpot,

loon,

nut,

nutbag,

nutter,

screwball,

wacko