bladderwrack n similar to and found with black rockweed n a common rockweed used in preparing kelp and as manure Usage(s) In 1937, three concoctions endorsed by Hauser"Slim" (containing the harmful drugs senna, bladderwrack, buckthorn bark), "Correcol" (consisting of weeds and gum), and Hauser . Synonym(s) Ascophyllum nodosum black rockweed bladder fucus tang Fucus vesiculosus