cetrarin \cet"rarin\, n. from cetraria islandica, the
   scientific name of iceland moss. chem.
   a white substance extracted from the lichen, iceland moss
   cetraria islandica. it consists of several ingredients,
   among which is cetraric acid, a white, crystalline, bitter
   substance.
   1913 webster
see also:
cetraria islandica 

cetraria islandica
     n : 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 syn: iceland moss, iceland lichen
see also:
iceland moss iceland lichen