/ Dictionary / Index O OMA: Meaning and Definition of Find definitions for: OMA Pronunciation: [key] orderly marketing agreement. -oma Pronunciation: [key] — pl. -omas, -omata. a noun suffix used to form names of tumors, of the kind specified by the base: fibroma; melanoma. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Om Omaha Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language