Source : Webster's Revised Unabridged Dictionary (1913)

Gruesome \Grue"some\, a.
   Same as {Grewsome}. [Scot.]

Grewsome \Grew"some\, Gruesome \Grue"some\, a. [From a word akin
   to Dan. gru horror, terror + -some; cf. D. gruwzaam, G.
   grausam. Cf. {Grisly}.]
   Ugly; frightful.

         Grewsome sights of war.                  --C. Kingsley.

Source : WordNet®

gruesome
     adj : shockingly repellent; inspiring horror; "ghastly wounds";
           "the grim aftermath of the bombing"; "the grim task of
           burying the victims"; "a grisly murder"; "gruesome
           evidence of human sacrifice"; "macabre tales of war and
           plague in the Middle ages"; "macabre tortures conceived
           by madmen" [syn: {ghastly}, {grim}, {grisly}, {macabre}]