The Collaborative International Dictionary of English v.0.48:

Philanthropy \Phi*lan"thro*py\, n. [L. philanthropia, Gr.
   filanqrwpi`a: cf. F. philanthropie.]
   Love to mankind; benevolence toward the whole human family;
   universal good will; desire and readiness to do good to all
   men; -- opposed to misanthropy. --Jer. Taylor.
   [1913 Webster]

   2. An active effort to promote human welfare; humanitarian
      activity. in this sense, it is an action, not merely a
      state of mind.
      [PJC]

   3. An organization whose purpose is to engage in
      philanthropy(2), and is supported by funds from one or a
      small number of wealthy individuals; a type of charity,
      the source of whose funds is typically from a wealthy
      individual or a corporation, or a trust fund established
      by a wealthy individual. It is distinguished from other
      charitable organizations in that the source of funds of
      other charities may come from a large number of sources,
      or from public solicitation.
      [PJC]

WordNet (r) 3.0 (2006):

philanthropy
    n 1: voluntary promotion of human welfare [syn: philanthropy,
         philanthropic gift]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "philanthropy":
   BOMFOG, Benthamism, Christian charity, Christian love, agape, aid,
   almsgiving, altruism, assistance, beneficence, benevolence,
   benevolent disposition, benevolentness, benignity, bigheartedness,
   brotherly love, caritas, charitableness, charity, contribution,
   do-goodism, donation, flower power, generosity, giving, goodwill,
   grace, grant, greatheartedness, help, humanitarianism,
   largeheartedness, largesse, liberality, love, love of mankind,
   magnanimity, patronage, philanthropism, thoughtfulness,
   utilitarianism, welfarism, well-disposedness