/ Dictionary / Index S subphylum: Meaning and Definition of Find definitions for: sub•phy•lum Pronunciation: (sub-fī'lum), [key] — pl. -la a category of related classes within a phylum. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: subphylum (Thesaurus) suboxide subpleural Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language