1686; from Middle French goumon (14th c.), from Middle Breton gwemon, from Old Breton goumon, from late Proto-Brythonic *gwɨmon (“seaweed”), from Proto-Celtic *wimmonā, from Proto-Indo-European *weyp- (“to wind, wrap around”); see also Welsh gwymon and Middle Irish femmain (modern Scottish Gaelic and Irish feamainn).