E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Erse (1 syl.).
The native language of the West Highlanders of Scotland, who are of Irish origin. It is a variant of Irish. Applied by the Scotch Lowlanders to the Highland dialect of Gaelic. In the eighteenth century Scotch was often called Erse, without distinction of Highland and Lowland; and Irish was spoken of as Irish Gaelic. The practice now is to limit the word Erse to Irish, and Gaelic to Scotch Highlanders.