The Collaborative International Dictionary of English v.0.48:

Moderate \Mod"er*ate\, v. t. [imp. & p. p. Moderated; p. pr. &
   vb. n. Moderating.]
   1. To restrain from excess of any kind; to reduce from a
      state of violence, intensity, or excess; to keep within
      bounds; to make temperate; to lessen; to allay; to
      repress; to temper; to qualify; as, to moderate rage,
      action, desires, etc.; to moderate heat or wind.
      [1913 Webster]

            By its astringent quality, it moderates the relaxing
            quality of warm water.                --Arbuthnot.
      [1913 Webster]

            To moderate stiff minds disposed to strive.
                                                  --Spenser.
      [1913 Webster]

   2. To preside over, direct, or regulate, as a public meeting
      or a discussion; as, to moderate a synod; to moderate a
      debate.
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

moderating \moderating\ adj.
   lessening in intensity or strength. Opposite of
   intensifying. [Narrower terms: tempering; weakening]
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

moderating
    adj 1: lessening in intensity or strength [ant: intensifying]