horse·shoe / ˈhôr(s)ˌshoō/ • n. a shoe for a horse formed of a narrow band of iron in the form of an extended circular arc and secured to the hoof with nails. ∎  a shoe of this kind or a representation of one, regarded as bringing good luck. ∎  something resembling this in shape: [as adj.] a horseshoe bend. ∎  (horseshoes) [treated as sing.] a game in which horseshoes are thrown at a stake in the ground.

horseshoe a shoe for a horse, traditionally regarded as bringing good luck.