/ Dictionary / Index S S star: Meaning and Definition of Find definitions for: S star Pronunciation: [key] — Astron. Astron. a relatively cool red giant having a surface temperature of about 2500 K and an absorption spectrum with strong lines of zirconium oxide. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. SST SSW Related Content Daily Word Quiz: tenacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language