The Collaborative International Dictionary of English v.0.48:

Roar \Roar\, v. i. [imp. & p. p. Roared; p. pr. & vvb. n.
   Roaring.] [OE. roren, raren, AS. r[=a]rian; akin to G.
   r["o]hten, OHG. r[=e]r[=e]n. [root]112.]
   1. To cry with a full, loud, continued sound. Specifically:
      (a) To bellow, or utter a deep, loud cry, as a lion or
          other beast.
          [1913 Webster]

                Roaring bulls he would him make to tame.
                                                  --Spenser.
          [1913 Webster]
      (b) To cry loudly, as in pain, distress, or anger.
          [1913 Webster]

                Sole on the barren sands, the suffering chief
                Roared out for anguish, and indulged his grief.
                                                  --Dryden.
          [1913 Webster]

                He scorned to roar under the impressions of a
                finite anger.                     --South.
          [1913 Webster]

   2. To make a loud, confused sound, as winds, waves, passing
      vehicles, a crowd of persons when shouting together, or
      the like.
      [1913 Webster]

            The brazen throat of war had ceased to roar.
                                                  --Milton.
      [1913 Webster]

            How oft I crossed where carts and coaches roar.
                                                  --Gay.
      [1913 Webster]

   3. To be boisterous; to be disorderly.
      [1913 Webster]

            It was a mad, roaring time, full of extravagance.
                                                  --Bp. Burnet.
      [1913 Webster]

   4. To laugh out loudly and continuously; as, the hearers
      roared at his jokes.
      [1913 Webster]

   5. To make a loud noise in breathing, as horses having a
      certain disease. See Roaring, 2.
      [1913 Webster]

   Roaring boy, a roaring, noisy fellow; -- name given, at the
      latter end Queen Elizabeth's reign, to the riotous fellows
      who raised disturbances in the street. "Two roaring boys
      of Rome, that made all split." --Beau. & Fl.

   Roaring forties (Naut.), a sailor's name for the stormy
      tract of ocean between 40[deg] and 50[deg] north latitude.
      [1913 Webster]