Erse Look up Erse at
"of or pertaining to the Celts of Ireland and Scotland," late 14c., an early Scottish variant of Old English Irisc or Old Norse Irskr "Irish" (for which see Irish (n.)). It was applied by Lowland Scots to the Gaelic speech of the Highlanders (which originally is from Ireland); the sense shifted 19c. from "Highlanders" to "Irish."