The Collaborative International Dictionary of English v.0.48:

Whoop \Whoop\, v. i. [imp. & p. p. Whooped; p. pr. & vb. n.
   Whooping.] [OE. houpen. See Hoop, v. i.]
   [1913 Webster]
   1. To utter a whoop, or loud cry, as eagerness, enthusiasm,
      or enjoyment; to cry out; to shout; to halloo; to utter a
      war whoop; to hoot, as an owl.
      [1913 Webster]

            Each whooping with a merry shout.     --Wordsworth.
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            When naught was heard but now and then the howl
            Of some vile cur, or whooping of the owl. --W.
                                                  Browne.
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   2. To cough or breathe with a sonorous inspiration, as in
      whooping cough.
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