The Collaborative International Dictionary of English v.0.48:

Ponder \Pon"der\, v. t. [imp. & p. p. Pondered; p. pr. & vb.
   n. Pondering.] [L. ponderare, fr. pondus, ponderis, a
   weight, fr. pendere to weigh: cf. F. pond['e]rer. See
   Pendant, and cf. Pound a weight.]
   [1913 Webster]
   1. To weigh. [Obs.]
      [1913 Webster]

   2. To weigh in the mind; to view with deliberation; to
      examine carefully; to consider attentively.
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            Ponder the path of thy feet.          --Prov. iv.
                                                  26.
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   Syn: To Ponder, Consider, Muse.

   Usage: To consider means to view or contemplate with fixed
          thought. To ponder is to dwell upon with long and
          anxious attention, with a view to some practical
          result or decision. To muse is simply to think upon
          continuously with no definite object, or for the
          pleasure it gives. We consider any subject which is
          fairly brought before us; we ponder a concern
          involving great interests; we muse on the events of
          childhood.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pondering \Pon"der*ing\, a.
   Deliberating. -- Pon"der*ing*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pondering
    adj 1: deeply or seriously thoughtful; "Byron lives on not only
           in his poetry, but also in his creation of the 'Byronic
           hero' - the persona of a brooding melancholy young man";
           [syn: brooding, broody, contemplative,
           meditative, musing, pensive, pondering,
           reflective, ruminative]