The Collaborative International Dictionary of English v.0.48:

Howl \Howl\, v. i. [imp. & p. p. Howled; p. pr. & vb. n.
   Howling.] [OE. houlen, hulen; akin to D. huilen, MHG.
   hiulen, hiuweln, OHG. hiuwil[=o]n to exult, h?wo owl, Dan.
   hyle to howl.]
   1. To utter a loud, protracted, mournful sound or cry, as
      dogs and wolves often do.
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            And dogs in corners set them down to howl.
                                                  --Drayton.
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            Methought a legion of foul fiends
            Environ'd me about, and howled in my ears. --Shak.
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   2. To utter a sound expressive of distress; to cry aloud and
      mournfully; to lament; to wail.
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            Howl ye, for the day of the Lord is at hand. --Is.
                                                  xiii. 6.
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   3. To make a noise resembling the cry of a wild beast.
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            Wild howled the wind.                 --Sir W.
                                                  Scott.
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   Howling monkey. (Zool.) See Howler, 2.

   Howling wilderness, a wild, desolate place inhabited only
      by wild beasts. --Deut. xxxii. 10.
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The Collaborative International Dictionary of English v.0.48:

Howl \Howl\, v. t.
   To utter with outcry. "Go . . . howl it out in deserts."
   --Philips.
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The Collaborative International Dictionary of English v.0.48:

Howl \Howl\, n.
   1. The protracted, mournful cry of a dog or a wolf, or other
      like sound.
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   2. A prolonged cry of distress or anguish; a wail.
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WordNet (r) 3.0 (2006):

howl
    n 1: a long loud emotional utterance; "he gave a howl of pain";
         "howls of laughter"; "their howling had no effect" [syn:
         howl, howling, ululation]
    2: the long plaintive cry of a hound or a wolf
    3: a loud sustained noise resembling the cry of a hound; "the
       howl of the wind made him restless"
    v 1: emit long loud cries; "wail in self-pity"; "howl with
         sorrow" [syn: howl, ululate, wail, roar, yawl,
         yaup]
    2: cry loudly, as of animals; "The coyotes were howling in the
       desert" [syn: howl, wrawl, yammer, yowl]
    3: make a loud noise, as of wind, water, or vehicles; "The wind
       was howling in the trees"; "The water roared down the chute"
       [syn: roar, howl]
    4: laugh unrestrainedly and heartily [syn: roar, howl]