/ Dictionary / Index S sidereal hour angle: Meaning and Definition of Find definitions for: side'real hour' an"gle Pronunciation: [key] — Astron. Astron. the angle, measured westward through 360°, between the hour circle passing through the vernal equinox and the hour circle of a celestial body. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sidereal day sidereal month Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language