/ Dictionary / Index E exotoxin: Meaning and Definition of Find definitions for: ex•o•tox•in Pronunciation: (ek"sō-tok'sin), [key] — n. Biochem. a soluble toxin excreted by a microorganism. Cf. endotoxin. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: exotoxin (Thesaurus) exoticism exotropia 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