Breadcrumb Home > Dictionary > Index L luminosity class: Meaning and Definition of Find definitions for: luminos'ity class" Pronunciation: [key] — Astron. Astron. a classification of stars of a given spectral type according to their luminosity, breaking them down into dwarfs, giants, and supergiants. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. luminosity luminous ✖ Related Content Daily Word Quiz: derogate Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language