What is the origin of gormless?

The British adjective gormless, “lacking in vitality or intelligence; stupid, dull, or clumsy,” with the variant spellings gaumless and gawm(b)less, is probably a respelling of gaumless by r-less speakers. Gaumless comes from the Northern English and Scots noun gaum “heed, attention,” from Old Norse gaumr, with the same meaning. Gormless entered English in the mid-18th century.