Precisely where the word 'cocktail' came from is uncertain. A popular piece of folklore describes how a Mexican princess called Xoctl offered a mixed drink to an American visitor to her father's court who confused her name with that of the drink itself.
Another suggestion is that the spoon used for mixing drinks reminded imbibing racegoers of the docked tails of non-thoroughbred horses, called cocktails. There are many other flights of fancy, but modern etymologists mostly agree that the word derives from coquetel, a French, wine-based drink.