From Tolkien Gateway

Sûza is the Westron word for "province, sphere of occupation, division of a realm",[1] visible in Sûza-t, "The Shire".[2]


Perhaps the second element -za related to the Adûnaic word zâyan ("land").[3]


"[...] actually the ON Old Norse and mod. Icelandic sýsla[4]> (Swed. syssla, Dan. syssel, now obsolete in sense amt, but occurring in place-names) was in mind when I said that the real untranslated name of the Shire was Súza [...] hence it was also said [...] that it was a 'district of well-ordered business'."[5]