/ Dictionary / Index R red seaweed: Meaning and Definition of Find definitions for: red' sea'weed Pronunciation: [key] any marine red alga, esp. one of the genus Polysiphonia, having a reddish, much branched thallus. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Red Sea redshank Related Content Daily Word Quiz: placid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language