The original definition of a cocktail, according to early cookbooks, is simple: spirits, bitters, sugar, and water. What’s less simple is determining where the term cocktail came from. It appeared printed in the U.S. for the first time in 1803, and even earlier in the U.K. Over the years a number of theories have been thrown around as to the origins of the term. Some think that it came from the French word coquetel, a kind of cup often used for serving drinks. Others give credit it to a novel by James Fenimore Cooper, in which a character regularly serves the drink (and which, presumably, Cooper would have been consuming as well). There is also a story of English troops in Mexico being served a drink that was mixed with a cola de gallo, or a cock’s tail.
Historian David Wondrich, however, published findings in 2016 that tell a different story. He traced the term through one of its ingredients – bitters – and its ingredients and uses back in the day. Turns out that a common early variety of bitters was made of ginger, though the word cocktail doesn’t come from a ginger drink. Rather, it comes from something of an odd practice. Horse sellers, looking to make their horses look more formidable at market, would give them ginger, which would cause the animals to cock their tails. The ginger bitters were meant to improve the drinker’s mood, the same effect it had on our equine companions.
Wondrich’s telling of his discovery is a fun read – check it out here: http://www.saveur.com/how-the-cocktail-got-its-name#page-3