loony

Adjective

• informal or slang terms for mentally irregular
  • it used to drive my husband balmy
    

Noun

• someone deranged and possibly dangerous

Related words

• Synonyms: 
  balmy , barmy , bats , batty , bonkers , buggy , cracked , crackers , daft , dotty , fruity , haywire , kooky , kookie , loco , loopy , crazy , looney , nutcase , weirdo