iceland moss(n = noun.plant) cetraria islandica, iceland lichen - lichen with branched flattened partly erect thallus that grows in mountainous and Arctic regions; used as a medicine or food for humans and livestock; a source of glycerol; Array
A kind of lichen (Cetraria Icelandica) found from the Arctic regions to the North Temperate zone. It furnishes a nutritious jelly and other forms of food, and is used in pulmonary complaints as a demulcent. [1913 Webster]