An anagram is a word formed by rearranging all the letters of another word, using each letter exactly once. These words use every letter from "UUESRS":
A very large, powerful, and savage extinct bovine animal (Bos urus / primigenius) anciently abundant in Europe. It appears to have still existed in the time of Julius Caesar. It had very large horns, and was hardly capable of domestication. Called also, ur, ure, and tur.