regio

plural regiones

1. planetary geologyastronomyAny large area of a planet or moon that is strongly differentiated from neighbouring areas by colour or albedo.
2. Ancient RomeA district of a city.

   The British School has unearthed a city of continuous houses, more than 400 feet long by 350 broad, whose many blocks or "insul[ae]" might seem almost to need the more elaborate grouping of the "regiones" of Pompeii.

   1907, Ronald M. Burrows, The Discoveries In Crete, page 27