/ Dictionary / Index S spongin: Meaning and Definition of Find definitions for: spon•gin Pronunciation: (spun'jin), [key] — n. a scleroprotein occurring in the form of fibers that form the skeleton of certain sponges. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. spongillafly spongioblast Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language