What does Bal mean?

With his chinos and polo he stood out right away as a typical bal at the party.

Dutch student slang. This is a Dutch word. You will hear it a lot at Dutch universities, student associations and in student houses.

People also use it more loosely for someone who looks or acts like a typical corps member. Even if they aren't a member at all. Think posh clothes, a loud voice and a lot of confidence. Also read about sociëteit and jasje dasje.