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]