The Collaborative International Dictionary of English v.0.48:

Hammer \Ham"mer\, v. t. [imp. & p. p. Hammered (-m[~e]rd); p.
   pr. & vb. n. Hammering.]
   1. To beat with a hammer; to beat with heavy blows; as, to
      hammer iron.
      [1913 Webster]

   2. To form or forge with a hammer; to shape by beating.
      "Hammered money." --Dryden.
      [1913 Webster]

   3. To form in the mind; to shape by hard intellectual labor;
      -- usually with out.
      [1913 Webster]

            Who was hammering out a penny dialogue. --Jeffry.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hammering
    n 1: the act of pounding (delivering repeated heavy blows); "the
         sudden hammer of fists caught him off guard"; "the pounding
         of feet on the hallway" [syn: hammer, pound,
         hammering, pounding]