Source : Webster's Revised Unabridged Dictionary (1913)

Sing \Sing\, v. t.
   1. To utter with musical infections or modulations of voice.

            And they sing the song of Moses, the servant of God,
            and the song of the Lamb.             --Rev. xv. 3.

            And in the darkness sing your carol of high praise.
                                                  --Keble.

   2. To celebrate is song; to give praises to in verse; to
      relate or rehearse in numbers, verse, or poetry. --Milton.

            Arms and the man I sing.              --Dryden.

            The last, the happiest British king, Whom thou shalt
            paint or I shall sing.                --Addison.

   3. To influence by singing; to lull by singing; as, to sing a
      child to sleep.

   4. To accompany, or attend on, with singing.

            I heard them singing home the bride.  --Longfellow.

Sing \Sing\, v. i. [imp. {Sung}or {Sang}; p. p. {Sung}; p. pr. &
   vb. n. {Singing}.] [AS. singan; akin to D. zingen, OS. & OHG.
   singan, G. singen, Icel. syngja, Sw. sjunga, Dan. synge,
   Goth. siggwan, and perhaps to E. say, v.t., or cf. Gr. ???
   voice. Cf. {Singe}, {Song}.]
   1. To utter sounds with musical inflections or melodious
      modulations of voice, as fancy may dictate, or according
      to the notes of a song or tune, or of a given part (as
      alto, tenor, etc.) in a chorus or concerted piece.

            The noise of them that sing do I hear. --Ex. xxxii.
                                                  18.

   2. To utter sweet melodious sounds, as birds do.

            On every bough the briddes heard I sing. --Chaucer.

            Singing birds, in silver cages hung.  --Dryden.

   3. To make a small, shrill sound; as, the air sings in
      passing through a crevice.

            O'er his head the flying spear Sang innocent, and
            spent its force in air.               --Pope.

   4. To tell or relate something in numbers or verse; to
      celebrate something in poetry. --Milton.

            Bid her . . . sing Of human hope by cross event
            destroyed.                            --Prior.

Source : WordNet®

sing
     v 1: deliver by singing; "Sing Christmas carols"
     2: produce tones with the voice; "She was singing while she was
        cooking"; "My brother sings very well"
     3: to make melodious sounds; "The nightingale was singing"
     4: make a whining, ringing, or whistling sound; "the kettle was
        singing"; "the bullet sang past his ear" [syn: {whistle}]
     5: divulge confidential information or secrets;  "Be
        careful--his secretary talks" [syn: {spill the beans}, {let
        the cat out of the bag}, {talk}, {tattle}, {blab}, {peach},
         {babble}, {babble out}, {blab out}] [ant: {keep quiet}]
     [also: {sung}, {singing}, {sang}]