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 "SOHDNAG":
One of several species of sea birds of the genus Puffinus; esp., P. major, the greater shearwarter, and P. Stricklandi, the black hagdon or sooty shearwater; -- called also hagdown, haglin, and hag. See Shearwater.