Source : Webster's Revised Unabridged Dictionary (1913)

Doggedness \Dog"ged*ness\, n.
   1. Sullenness; moroseness. [R.]

   2. Sullen or obstinate determination; grim resolution or
      persistence.

Source : WordNet®

doggedness
     n : persistent determination [syn: {perseverance}, {persistence},
          {persistency}, {tenacity}, {tenaciousness}, {pertinacity}]