/ Dictionary / Index O oncidium: Meaning and Definition of Find definitions for: on•cid•i•um Pronunciation: (on-sid'ē-um), [key] — n. any of numerous tropical American orchids of the genus Oncidium, having clusters of flowers showing great variety in size, form, and color. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: oncidium (Thesaurus) onchocerciasis onco- Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language