regio (Constantinople), in ancient Constantinople as a name for the 12 quartiers of the city of Constantinople, made in analogy with those of Rome.

regio (anatomy) - in anatomy, to describe certain areas on the body.

Regio (pl. regiones) is the Latin word for 'region.' It may mean:

regio (Rome), in ancient Rome as a name for quartiers of the city of Rome.

regio (astronomy) - in planetary geology, a large area of a planet or moon that are strongly differentiated in colour or albedo.