West Frisia (/ˈfriːʒə/; Latin: Frisia Occidentalis; West Frisian: West-Fryslân) is a term that, when used in an international context, refers to the traditionally Frisian areas that are located west of the Dollart (i.e. in the present-day Netherlands).
In its narrowest sense, the term is synonymous with the province of Friesland.
[2] In its broadest sense, it also includes the Ommelanden and the region of West Friesland.
The Lex Frisionum, for instance, distinguishes three districts of Frisia, defining West Frisia as the territory "between Zwin and Vlie" (present-day Holland and Zeeland) and East Frisia as the territory "between Lauwers and Weser".
At the time, the region between the Vlie and the Lauwers was known as "Middle Frisia".