How do you say bestman in greek?

There isn't a single, direct translation for "best man" in Greek that captures the same cultural nuance. The closest you'd get would depend on the context:

* Κουμπάρος (koumparos): This is the most common and closest equivalent. A koumparos is a "best man" in the sense that he's a very close friend of the groom who plays a significant role in the wedding ceremony. However, the role of a koumparos can sometimes extend beyond the Western concept of a best man.

* Παράνυμφος (paranymphos): This word literally translates to "bridesman" or "attendant" and was traditionally used for both the groom's and bride's attendants. While less common now, it could be used in a more formal or traditional context.

Therefore, κουμπάρος (koumparos) is generally the best and most accurate translation to use.