A surname of Scottish origin; sometimes used in the phrase 'the real McCoy,' meaning the genuine or authentic article.
From Scottish Gaelic 'Mac Aodha' (son of Aodh), which became anglicized as McCoy. The phrase 'the real McCoy' possibly derives from bootlegger Norman Selby (known as 'Kid' McCoy) or the Scottish Clan McCoy's reputation for quality goods.
Nobody is completely sure why 'the real McCoy' means 'authentic,' but what's fascinating is that this phrase shows how surnames can become part of everyday language—you're not actually talking about a person anymore, you're using their name as a symbol of trustworthiness.
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