Hagdon \Hag"don\ (h[a^]g"d[o^]n), n. (Zool.) One of several species of sea birds of the genus {Puffinus}; esp., {Puffinus major}, the greater shearwarter, and {Puffinus Stricklandi}, the black hagdon or sooty shearwater; -- called also {hagdown}, {haglin}, and {hag}. See {Shearwater}. [1913 Webster]