nounAstronomy & Geometry
Half of a diameter; radius.
More example sentences
- The moon will, at the full, be totally eclipsed, if its latitude is less than the difference between its own semidiameter, and that of the earth's shadow.
- By the semidiameter of a celestial object, is meant the angle which the radius of its apparent circular disc subtends at the eye of the observer.
late Middle English: from late Latin.
Definition of semidiameter in:
- The British & World English dictionary