kelp

noun

• a large brown seaweed that typically has a long, tough stalk with a broad frond divided into strips: a large bed of kelp [count noun]:there are several kelps found in the lower zones

  • Family Laminariaceae, class Phaeophyceae, including the genera Laminaria (used in some areas as manure) and Macrocystis (harvested in the US as a source of algin)
• the calcined ashes of seaweed, used as a source of various salts.