The Collaborative International Dictionary of English v.0.48:

Whimper \Whim"per\, v. i. [imp. & p. p. Whimpered; p. pr. &
   vb. n. Whimpering.] [Cf. Scot. whimmer, G. wimmern.]
   To cry with a low, whining, broken voice; to whine; to
   complain; as, a child whimpers.
   [1913 Webster]

         Was there ever yet preacher but there were gainsayers
         that spurned, that winced, that whimpered against him?
                                                  --Latimer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Whimper \Whim"per\, v. t.
   To utter in alow, whining tone.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Whimper \Whim"per\, n.
   A low, whining, broken cry; a low, whining sound, expressive
   of complaint or grief.
   [1913 Webster]

WordNet (r) 3.0 (2006):

whimper
    n 1: a complaint uttered in a plaintive whining way [syn:
         whimper, whine]
    v 1: cry weakly or softly; "she wailed with pain" [syn: wail,
         whimper, mewl, pule]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "whimper":
   bawl, blubber, boohoo, break down, burst into tears, cry,
   dissolve in tears, dolorous tirade, drop a tear, greet, groan,
   howl, jeremiad, keen, lament, moan, murmur, mutter, outcry, plaint,
   planctus, pule, scream, shed tears, snivel, sob, tirade, ululation,
   wail, wail of woe, weep, whine, yammer, yawp, yowl