A horseshoe is a U-shaped metal object that is nailed to the hooves of horses to protect them from wear and tear. The two crossword solutions for the term 'horseshoe' are 'CRAB' and 'calk'. A CRAB is a type of horseshoe that has a wide, flat sole and a deep crease in the middle. Calk is a type of horseshoe that has a raised lip on the outside edge and a flat sole. Both types of horseshoes are designed to provide protection and traction for horses.