Examples from the Web for semidiameter
Each semicircular niche was about a foot in its semidiameter.Passages From the French and Italian Notebooks, Volume 1|Nathaniel Hawthorne
As the semidiameter was only 28 inches, this large tree could have been but 168 years old.Missionary Travels and Researches in South Africa|David Livingstone
Whereby it dothe well appeare, that the side of anye sisangle made in a circle, is equalle to the semidiameter of the same circle.
Then at the ende of eche semidiameter, I draw a touche line, whiche shall make righte angles with the semidiameter.
For a right line either from the center unto the touch-point; or from the touch point unto the center is radius or semidiameter.The Way To Geometry|Peter Ramus