An ascot is a wide necktie that resembles a small scarf. If you aren't a British earl or Austin Powers, wearing an ascot could be considered a fashion risk. Ascot definition, a necktie or scarf with broad ends, tied and arranged so that the ends are laid flat, one across the other, sometimes with a pin to secure them. a man's broad silk necktie. Meaning, pronunciation, example sentences, and more from Oxford Dictionaries.