Of or relating to the class Phaeophyceae, which comprises the brown algae.
noun
An alga of the class Phaeophyceae; a brown alga.
Origin
Early 20th century; earliest use found in Benjamin Jackson (1846–1927). From scientific Latin Phaeophyceae, class name (A. de Bary in Bot. Zeitung 39 14/2; from ancient Greek ϕαιός grey + ϕῦκος seaweed + scientific Latin -eae: see -eous) + -an.