noun, plural: phyla or phylums
(1) A taxonomic rank at the level below Kingdom and above Class in biological classification, especially of animals.
(2) A group of Classes with similar distinctive characteristics.
Examples: Class Mammalia (mammals), Class Aves (birds) and Class Ascidiacea (sea squirts) all belong to Chordate Phylum, which is a group of animals that have notochords at some time in their life cycle. Aside from Chordata, other well known phyla are the Mollusca, Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Arthropoda and Echinodermata, which all belong to Kingdom Animalia.
Word origin: New Latin phymacrlum, from Greek phūlon, class.
See also: taxonomy.