What is the greek word for one group?

There isn't one single perfect Greek word for "one group," as the best translation depends on the context. However, here are a few options with slightly different nuances:

* μία ομάδα (mia omada): This is the most straightforward translation. "μία" (mia) means "one" and "ομάδα" (omada) means "group" or "team." This works well for most general contexts.

* ἕν σύνολον (hen synolon): "ἕν" (hen) means "one" and "σύνολον" (synolon) means "whole," "set," or "collection." This emphasizes the unity of the group as a single entity.

* μία συλλογή (mia syllogí): "μία" (mia) means "one" and "συλλογή" (syllogí) means "collection." This is suitable if the group is formed by bringing things together.

The best choice will depend on what kind of group you're referring to and what aspect you want to emphasize.