1. (noun) someone deranged and possibly dangerous

• crazy
• looney
• nutcase
• weirdo

2. (adjective) informal or slang terms for mentally irregular

• around the bend
• balmy
• barmy
• bats
• batty
• bonkers
• buggy
• cracked
• crackers
• daft
• dotty
• fruity
• haywire
• kookie
• kooky
• loco
• loopy
• nuts
• nutty
• round the bend
• wacky
• whacky

1. (adjective) informal or slang terms for mentally irregular

• insane

1. (noun) someone deranged and possibly dangerous

• lunatic
• madman
• maniac

1. (adjective) informal or slang terms for mentally irregular

• addle-head
• addlehead
• birdbrain
• loon
• craziness
• daftness
• flakiness
• kook
• odd fellow
• odd fish
• odd man out
• queer bird
• queer duck