: any of several large brown algae especially of the genus Laminaria including some used as a source of iodine and other chemicals, as fertilizer, and sometimes as food
History and Etymology for oarweed
English dialect oare, ore seaweed (from Middle English ware, from Old English wār) + English weed; akin to Old English wīr myrtle, Middle Dutch wier seaweed, and probably to Old Norse visk wisp