The word was originally used to describe animals that live in flocks — it's from the Latin word grex, meaning "herd." Not surprisingly, people began using it to describe humans who liked being in groups. Today biologists still speak of gregarious species, but you're more likely to hear it in reference to people. Despite what you might suspect, it has no historical connection to the name Gregory — but if you know an outgoing fellow with that name, you could call him Greg-arious.