The Collaborative International Dictionary of English v.0.48:

Yaup \Yaup\, v. i. [See Yap, and Yelp.]
   To cry out like a child; to yelp. [Scot. & Colloq. U. S.]
   [Written also yawp.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Yawp \Yawp\, v. & n.
   See Yaup.
   [1913 Webster]

WordNet (r) 3.0 (2006):

yawp
    v 1: make a raucous noise [syn: yawp, bawl]
    2: complain whiningly [syn: whine, grizzle, yammer,
       yawp]