Gau (Dutch: gouw, Frisian: gea or goa) is a Germanic term for a region within a country, often a former or actual province. It was used in medieval times, when it can be seen as roughly corresponding to an English shire. The administrative use of the term was revived as a subdivision during the period of Nazi Germany in 1933–1945. It still appears today in regional names, such as the Rheingau or Allgäu.
The Germanic word is reflected in Gothic gavi (neuter; genitive gaujis) and early Old High German gewi, gowi (neuter) and in some compound names still -gawi as in Gothic (e.g. Durgawi "Thurgau", Alpagawi "Allgäu"), later gâi, gôi, and after loss of the stem suffix gaw, gao, and with motion to the feminine as gawa besides gowo (from gowio). Old Saxon shows further truncation to gâ, gô. As a gloss of Latin: pagus, a Gau is analogous with a pays of feudal France.
Old English, by contrast, has only traces of the word, which was ousted by scire from an early time, in names such as Noxga gā, Ohtga gā and perhaps in gōman, ġēman (yeoman), which would then correspond to the Old High German gaumann (Grimm) although the Oxford English Dictionary prefers connection of yeoman to young.