| the usual major subdivision of a family or subfamily in the classification of organisms, usually consisting of more than one species |
| transfer of information from one cell or molecule to another, as by chemical or electrical signals |
phylum phy·lum (fī'ləm)
n. pl. phy·la (-lə)
A taxonomic category that is a primary division of a kingdom and ranks above a class in size.
| phylum (fī'ləm) Pronunciation Key
Plural phyla A group of organisms ranking above a class and below a kingdom. See Table at taxonomy. |
plur. phyla
One of the major divisions of the kingdoms of living things; the second-largest standard unit of biological classification. The arthropods, chordates, and mollusks are phyla. Phyla in the plant kingdom are frequently called divisions. (See Linnean classification.)