*merg-

"of or pertaining to the Welsh" and their kindred, the Cornish and Bretons, by 1833, from Welsh Cymru "Wales," Cymry "the Welsh," plural of Cymro, probably from ancient combrox "compatriot," from British Celtic *kom-brogos, from collective prefix *kom- (see com-) + *brogos "district," from PIE root *merg- "boundary, border." Compare Allobroges, name of a warlike people in Gallia Narbonensis, literally "those from another land." As from 1833 as a noun, "the language of the Cymry."

"act of marking off limits or boundaries," 1737, from Spanish linea de demarcacion or Portuguese linha de demarcaçao, name of the line laid down by Pope Alexander VI on May 4, 1493, dividing the New World between Spain and Portugal on a line 100 leagues west of the Cape Verde Islands. Applied from 1801 to other lines dividing regions. From Spanish de- (see de-) + marcar "to mark the boundaries of," from a Germanic source (see mark (n.1)).