From Longman Dictionary of Contemporary Englishhorseshoehorse‧shoe /ˈhɔːʃ-ʃuː, ˈhɔːs- $ ˈhɔːr-/ noun [countable] 1 
TTBa U-shaped piece of iron that is fixed onto the bottom of a horse’s foot2 LUCKYan object in the shape of a horseshoe that is a sign of good luck
TTBa U-shaped piece of iron that is fixed onto the bottom of a horse’s foot2 LUCKYan object in the shape of a horseshoe that is a sign of good luckExamples from the Corpus
horseshoe• The present blacksmith's shop was built around 1840 and has a unique entrance in the shape of a horseshoe.• You will see a lot of men pitching horseshoes. 