Source : Webster's Revised Unabridged Dictionary (1913)

Pooh-pooh \Pooh`-pooh"\, v. t.
   To make light of; to treat with derision or contempt, as if
   by saying pooh! pooh! [Colloq.] --Thackeray.

Source : WordNet®

pooh-pooh
     v 1: express contempt about
     2: reject with contempt; "She spurned his advances" [syn: {reject},
         {spurn}, {freeze off}, {scorn}, {disdain}, {turn down}]