\Croon\ (kr??n), v. i. [OE. croinen, cf. D. kreunen to
moan. ?24.]
1. To make a continuous hollow moan, as cattle do when in
   pain. [Scot.] --Jamieson.
2. To hum or sing in a low tone; to murmur softly.
         Here an old grandmother was crooning over a sick
         child, and rocking it to and fro.     --Dickens.

\Croon\, v. t. [imp. & p. p. {Crooned} (kr??nd); p. pr. &
vb. n. {Crooning}.]
1. To sing in a low tone, as if to one's self; to hum.
         Hearing such stanzas crooned in her praise. --C.
                                               Bront?.
2. To soothe by singing softly.
         The fragment of the childish hymn with which he sung
         and crooned himself asleep.           --Dickens.

\Croon\, n.
1. A low, continued moan; a murmur.
2. A low singing; a plain, artless melody.