The Collaborative International Dictionary of English v.0.48:

Mewl \Mewl\, v. i. [imp. & p. p. Mewled; p. pr. & vb. n.
   Mewling.] [Cf. F. miauler to mew, E. mew to cry as a cat.
   Cf. Miaul.]
   To cry, as a young child; to squall. [Written also meawl.]
   --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mewl
    v 1: cry weakly or softly; "she wailed with pain" [syn: wail,
         whimper, mewl, pule]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "mewl":
   bark, bawl, bay, bell, bellow, blare, blat, blate, bleat, bray,
   call, caterwaul, cry, give tongue, give voice, howl, low, meow,
   mew, miaow, moo, neigh, nicker, pule, roar, screak, scream,
   screech, squall, squeak, squeal, troat, ululate, wail, whicker,
   whine, whinny, yap, yawl, yawp, yelp, yip, yowl