1. A reciprocal group action
   - return, getting even

Type of: group action

• idiopathic disease
• idiopathic disorder
• idiopathic hemochromatosis
• idiopathic thrombocytopenic purpura
• idiopathy
• idiosyncrasy
• idiosyncratic
• idiot
• idiot board
• idiot box
• idiot light
• idiot savant
• idiotic
• idiotically
• idiotism
• Iditarod
• Iditarod Trail
• Iditarod Trail Dog Sled Race
• idle
• idle pulley
• idle talk
• idle wheel
• idle words
• idleness
• idler