/ Dictionary / Index I indusium: Meaning and Definition of Find definitions for: in•du•si•um Pronunciation: (in-d'zē-um, -zhē-um, -dy'-), [key] — pl. -si•a any of several structures having a netlike or skirtlike shape, as the membranous overgrowth covering the sori in ferns. an enveloping layer or membrane. a thin layer of gray matter on the corpus callosum. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: indusium (Thesaurus) indusiate industrial Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language