English, a Roman ethnic name meaning "a woman from Sidon (a place in Phoenicia)".  It has been in occasional use since the Middle Ages, unlike the male form, Sidonius, which has seldom, if ever, been used. 

The Czech male name Zdeněk is very popular as are its female variants, Zdeňka, Zdenka and Zdena.

There has been some confusion with the Greek sindon, "winding-sheet" but this is unconnected.