Source : Webster's Revised Unabridged Dictionary (1913)

Gruff \Gruff\, a. [Compar. {Gruffer}; superl. {Gruffest}.] [D.
   grof; akin to G. grob, OHG. gerob, grob, Dan. grov, Sw. grof,
   perh. akin to AS. rc['o]fan to break, Z. reavc, rupture, g-
   standing for the AS. prefix ge-, Goth. ga-.]
   Of a rough or stern manner, voice, or countenance; sour;
   surly; severe; harsh. --Addison.

         Gruff, disagreeable, sarcastic remarks.  --Thackeray.
   -- {Gruff"ly}, adv. -- {Gruff"ness}, n.

Source : WordNet®

gruff
     adj 1: brusque and surly and forbidding; "crusty remarks"; "a
            crusty old man"; "his curmudgeonly temper"; "gruff
            manner"; "a gruff reply" [syn: {crusty}, {curmudgeonly},
             {ill-humored}, {ill-humoured}]
     2: deep and harsh sounding as if from shouting or illness or
        emotion; "gruff voices"; "the dog's gruff barking";
        "hoarse cries"; "makes all the instruments sound powerful
        but husky"- Virgil Thomson [syn: {hoarse}, {husky}]