Source : Webster's Revised Unabridged Dictionary (1913)

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.

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

         Namby-pamby madrigals of love.           --W. Gifford.

Source : WordNet®

namby-pamby
     adj : weak in willpower [syn: {spineless}, {wishy-washy}]
     n : an insipid weakling who is foolishly sentimental