It's the term used for Dutch as spoken in Belgium; in it, Antwerp is Antwerpen
Hence the name Antwerpen, from Dutch hand werpen, akin to Old English 
hand and... [DOC] [TLE] Flemish - Wikipedia [PAR] Flemish (Vlaams), also called Flemish Dutch (Vlaams-Nederlands), Belgian 
Dutch or Southern Dutch (Zuid-Nederlands), refers to any of the varieties of the 
Dutch language spoken in Flanders, the northern part of Belgium.