Sthenno is rooted in the word sthenos (= strength, might). While this and other names including masculine counterparts based on sthenos stand independently, they are more commonly recognized in compound names like
Demosthenes,
Kleisthenes and Kallisthenia (itself the root for callisthenics).
And because Greek is also the language of science and medicine you will find it in many related terms, as the link provided by Mr. Evans attests.