/ Dictionary / Index I immersionism: Meaning and Definition of Find definitions for: im•mer•sion•ism Pronunciation: (i-mûr'zhu-niz"um, -shu-), [key] — n. the doctrine that immersion is essential to Christian baptism. the practice of baptism by immersion. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. immersion heater immersion objective 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