Its source is a Gaelic expression meaning "A Celt."
This term was first used in English to designate the Highland Celts of Scotland. Over time it has come to designate the Irish as well.
Long before it came into English, Gael was a self-descriptive term used by Scots and Irish alike. The Scots term Gaidheal probably evolved from the Irish goidel, and some authorities trace this back to the Old Celtic word gwydd, meaning ''wild.''