COCKTAIL/S noun 1. = an alcoholic drink consisting of a spirit or spirits mixed with other ingredients, such as fruit juice or cream. "a cocktail bar" . . . . . . ... ... 2 = a dish consisting of small pieces of food, typically served cold as a starter. "we began with prawn and avocado cocktail"
The Oxford English Dictionary affirms the original use of 'cocktail' was to describe a horse with a tail like a cock's - that is to say, a docked tail, which stuck up, rather than hung down. That came to mean a racehorse that was mixed - not thoroughbred. Cocktail - Wikipedia