The Collaborative International Dictionary of English v.0.48:

Inwardly \In"ward*ly\, adv. [AS. inweardlice.]
   [1913 Webster]
   1. In the inner parts; internally.
      [1913 Webster]

            Let Benedick, like covered fire,
            Consume away in sighs, waste inwardly. --Shak.
      [1913 Webster]

   2. Toward the center; inward; as, to curve inwardly.
      [1913 Webster]

   3. In the heart or mind; mentally; privately; secretly; as,
      he inwardly repines.
      [1913 Webster]

   4. Intimately; thoroughly. [Obs.]
      [1913 Webster]

            I shall desire to know him more inwardly. --Beau. &
                                                  Fl.
      [1913 Webster]

WordNet (r) 3.0 (2006):

inwardly
    adv 1: with respect to private feelings; "inwardly, she was
           raging" [syn: inwardly, inside] [ant: outwardly]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "inwardly":
   by birth, by nature, centrally, congenitally, deeply, genetically,
   immanently, in, inland, inly, innately, inshore, interiorly,
   internally, intimately, intrinsically, inward, inwards, naturally,
   originally, primally, primitively, profoundly, under the surface,
   withinwards