Meaning of sidereal hour angle

side'real hour' an"gle

Pronunciation: [key]
— Astron. Astron.
  1. 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.