/ Dictionary / Index I implacental: Meaning and Definition of Find definitions for: im•pla•cen•tal Pronunciation: (im"plu-sen'tl), [key] — adj. having no placenta, as a monotreme or marsupial. —n. an implacental mammal. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. implacable implant Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language