The Collaborative International Dictionary of English v.0.48:

Waul \Waul\, v. i. [Of imitative origin.]
   To cry as a cat; to squall; to wail. [Written also wawl.]
   [1913 Webster]

         The helpless infant, coming wauling and crying into the
         world.                                   --Sir W.
                                                  Scott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

waul
    v 1: make high-pitched, whiney noises [syn: squall, waul,
         wawl]