Source : Webster's Revised Unabridged Dictionary (1913)

Croak \Croak\ (kr?k), v. i. [imp. & p. p. {Croaked}. (kr?kt); p.
   pr. & vb. n. {Croaking}.] [From the primitive of AS.
   cracettan to croak as a raven; akin to G. kr?chzen to croak,
   and to E. creak, crake.]
   1. To make a low, hoarse noise in the throat, as a frog, a
      raven, or a crow; hence, to make any hoarse, dismal sound.

            Loud thunder to its bottom shook the bog, And the
            hoarse nation croaked.                --Pope.

   2. To complain; especially, to grumble; to forebode evil; to
      utter complaints or forebodings habitually.

            Marat . . . croaks with reasonableness. --Carlyle.

Croak \Croak\, v. t.
   To utter in a low, hoarse voice; to announce by croaking; to
   forebode; as, to croak disaster.

         The raven himself is hoarse, That croaks the fatal
         entrance of Duncan.                      --Shak.

         Two ravens now began to croak Their nuptial song.
                                                  --Wordsworth.

Croak \Croak\, n.
   The coarse, harsh sound uttered by a frog or a raven, or a
   like sound.

Source : WordNet®

croak
     n : a harsh hoarse utterance (as of a frog) [syn: {croaking}]
     v 1: die; "The old man finally kicked the bucket" [syn: {kick the
          bucket}, {cash in one's chips}, {buy the farm}, {conk},
          {give-up the ghost}, {drop dead}, {pop off}, {choke}, {snuff
          it}]
     2: utter a hoarse sound, like a raven [syn: {cronk}]
     3: make complaining remarks or noises under one's breath; "she
        grumbles when she feels overworked" [syn: {murmur}, {mutter},
         {grumble}, {gnarl}]