/ Dictionary / Index M mastodon: Meaning and Definition of Find definitions for: mas•to•don Pronunciation: (mas'tu-don"), [key] — n. a massive, elephantlike mammal of the genus Mammut (Mastodon), that flourished worldwide from the Miocene through the Pleistocene epochs and, in North America, into recent times, having long, curved upper tusks and, in the male, short lower tusks. a person of immense size, power, influence, etc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mastodon (Thesaurus) mastocytosis mastoid Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language