The Collaborative International Dictionary of English v.0.48:

Wail \Wail\, v. t. [imp. & p. p. Wailed; p. pr. & vb. n.
   Wailing.] [OE. wailen, weilen, probably fr. Icel. v[ae]la;
   cf. Icel. v[ae], vei, woe, and E. wayment, also OE. wai, wei,
   woe. Cf. Woe.]
   To lament; to bewail; to grieve over; as, to wail one's
   death. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

wailing
    adj 1: vocally expressing grief or sorrow or resembling such
           expression; "lamenting sinners"; "wailing mourners"; "the
           wailing wind"; "wailful bagpipes"; "tangle her desires
           with wailful sonnets"- Shakespeare [syn: lamenting,
           wailing, wailful]
    n 1: loud cries made while weeping [syn: wailing, bawling]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "wailing":
   acute, argute, bawling, bemoaning, bewailing, blatant, creaky,
   crying, ear-piercing, grieving, howling, in mourning, keen,
   keening, lamentation, lamenting, lowing, moaning, mourning,
   mugient, penetrating, piercing, piping, puling, reedy, screaky,
   screeching, screechy, sharp, shrieking, shrieky, shrill, sorrow,
   sorrowing, squeaking, squeaky, thin, ululant, ululation, whining,
   whistling