/ Dictionary / Index O octad: Meaning and Definition of Find definitions for: oc•tad Pronunciation: (ok'tad), [key] — n. a group or series of eight. an element, atom, or group having a valence of eight. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: octad (Thesaurus) octachord octadecanoic acid Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language