/ Dictionary / Index O onomasticon: Meaning and Definition of Find definitions for: on•o•mas•ti•con Pronunciation: (on"u-mas'ti-kon", -kun), [key] — n. a list or collection of proper names. a list or collection of specialized terms, as those used in a particular field or subject area. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: onomasticon (Thesaurus) onomastic onomastics Related Content Daily Word Quiz: nonchalant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language