DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   Pshaw \Pshaw\, interj. [Of imitative origin.]
      Pish! pooch! -- an exclamation used as an expression of
      contempt, disdain, dislike, etc. [Written also psha.]
      [1913 Webster]