The Collaborative International Dictionary of English v.0.48:

Namby-pamby \Nam"by-pam`by\, n. [From Ambrose Phillips, in
   ridicule of the extreme simplicity of some of his verses.]
   Talk or writing which is weakly sentimental or affectedly
   pretty. --Macaulay.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Namby-pamby \Nam"by-pam`by\, a.
   1. Affectedly pretty; weakly sentimental; finical; insipid.
      --Thackeray.
      [1913 Webster]

            Namby-pamby madrigals of love.        --W. Gifford.
      [1913 Webster]

   2. Indecisive or weak; lacking firmness or resolve; -- of
      actions and policies.
      [PJC]

WordNet (r) 3.0 (2006):

namby-pamby
    adj 1: weak in willpower, courage or vitality [syn: namby-
           pamby, gutless, spineless, wishy-washy]
    n 1: an insipid weakling who is foolishly sentimental