/ Dictionary / Index S sea onion: Meaning and Definition of Find definitions for: sea' on"ion Pronunciation: [key] Also calleda Mediterranean plant, Urginea maritima, of the lily family, yielding medicinal squill. a squill, Scilla verna, of the Isle of Wight, having narrow leaves and clusters of violet flowers. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Sea of Tranquillity sea otter 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