/ Dictionary / Index P period-luminosity relation: Meaning and Definition of Find definitions for: pe'ri•od-lu•mi•nos'i•ty rela"tion Pronunciation: (pēr'ē-ud-l"mu-nos'i-tē), [key] — Astron. Astron. the relationship between the period of light variation and of the absolute magnitude of Cepheid variable stars. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. periodization period of revolution 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