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]

Moby Thesaurus II by Grady Ward, 1.0:

118 Moby Thesaurus words for "yawp":
   bark, battle cry, bawl, bay, beef, bell, bellow, bellyache, bitch,
   blare, blat, blate, bleat, blow off, blubber, boom, bray, breathe,
   buzz, cackle, call, caterwaul, caw, chant, cheer, chirp, coo, crab,
   crow, cry, cry out, dolorous tirade, drawl, exclaim, flute, fuss,
   gasp, give tongue, give voice, groan, growl, grunt, hail, halloo,
   hiss, holler, hollo, hoot, howl, hurrah, jeremiad, keen, lament,
   lilt, low, make an outcry, meow, mew, mewl, miaow, moan, moo,
   mumble, murmur, mutter, neigh, nicker, outcry, pant, pipe, plaint,
   planctus, pule, rallying cry, roar, rumble, screak, scream,
   screech, shout, shriek, sibilate, sigh, sing, snap, snarl, snort,
   sob, squall, squawk, squeak, squeal, thunder, tirade, troat,
   trumpet, twang, ululate, ululation, wail, wail of woe, war cry,
   war whoop, warble, whicker, whimper, whine, whinny, whisper, whoop,
   yammer, yap, yawl, yell, yelp, yip, yo-ho, yowl