/ Dictionary / Index S sidereal year: Meaning and Definition of Find definitions for: side'real year' Pronunciation: [key] — Astron. Astron. year (def. 4c). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sidereal time siderite Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language