|Definition - Another more literary name for both Scottish and Irish Gaelic.|
Etymology - The word was coined as a Scottish variant of the Old English Irisc, Irish. For some reason, it became the name that Lowland Scots called the Gaelic speech of the Highland Scots.
Oxford English Dictionary - Its first citation is from about 1375:
"Thow Scot, abyde … Ane Ersche mantill it war thi kynd to wer."
(1470 Henry Wallace i. 217)