Source : Webster's Revised Unabridged Dictionary (1913)

Knobby \Knob"by\, a. [From {Knob}.]
   1. Full of, or covered with, knobs or hard protuberances.
      --Dr. H. More.

   2. Irregular; stubborn in particulars. [Obs.]

            The informers continued in a knobby kind of
            obstinacy.                            --Howell.

   3. Abounding in rounded hills or mountains; hilly. [U.S.]
      --Bartlett.

Source : WordNet®

knobby
     adj : having knobs; "had knobbly knees" [syn: {knobbly}]