/ Dictionary / Index O orbital index: Meaning and Definition of Find definitions for: or'bital in'dex Pronunciation: [key] — Craniom. Craniom. the ratio of the maximum breadth to the maximum height of the orbital cavity multiplied by 100. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. orbitale orbital quantum number Related Content Daily Word Quiz: pugilist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language