/ Dictionary / Index R red algae: Meaning and Definition of Find definitions for: red' al'gae Pronunciation: [key] marine algae of the phylum Rhodophyta, in which the chlorophyll is masked by a red or purplish pigment. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. red alert redan Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language