screwball

Adjective

• foolish; totally unsound
  • a crazy scheme
    
  • half-baked ideas
    
  • a screwball proposal without a prayer of working
    

Noun

• a pitch with reverse spin that curves toward the side of the plate from which it was thrown

• a whimsically eccentric person

Related words

• Synonyms: 
  crazy , half-baked , softheaded , crackpot , crank , nut , nut case , fruitcake