(1):

(n.) The coarse, harsh sound uttered by a frog or a raven, or a like sound.

(2):

(v. i.) To make a low, hoarse noise in the throat, as a frog, a raven, or a crow; hence, to make any hoarse, dismal sound.

(3):

(v. i.) To complain; especially, to grumble; to forebode evil; to utter complaints or forebodings habitually.

(4):

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