/ 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: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language