NOUN (1)

1. a shout to attract attention;
- Example: "he gave a great halloo but no one heard him"


VERB (2)

1. urge on with shouts;
- Example: "halloo the dogs in a hunt"

2. shout `halloo', as when greeting someone or attracting attention;

The Collaborative International Dictionary of English v.0.48:

Halloo \Hal*loo"\, interj. [OE. halow. See Halloo, n.]
   An exclamation to call attention or to encourage one. Now
   mostly replaced by hello.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Halloo \Hal*loo"\ (h[a^]l*l[=oo]"), n. [Perh. fr. ah + lo; cf.
   AS. eal[=a], G. halloh, F. haler to set (a dog) on. Cf.
   Hollo, interj.]
   A loud exclamation; a call to invite attention or to incite a
   person or an animal; a shout.
   [1913 Webster]

         List! List! I hear
         Some far off halloo break the silent air. --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Halloo \Hal*loo"\, v. i. [imp. & p. p. Hallooed (-l[=oo]d");
   p. pr. & vb. n. Hallooing.]
   To cry out; to exclaim with a loud voice; to call to a
   person, as by the word halloo.
   [1913 Webster]

         Country folks hallooed and hooted after me. --Sir P.
                                                  Sidney.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Halloo \Hal*loo"\, v. t.
   1. To encourage with shouts.
      [1913 Webster]

            Old John hallooes his hounds again.   --Prior.
      [1913 Webster]

   2. To chase with shouts or outcries.
      [1913 Webster]

            If I fly . . . Halloo me like a hare. --Shak.
      [1913 Webster]

   3. To call or shout to; to hail. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

halloo
    n 1: a shout to attract attention; "he gave a great halloo but
         no one heard him"
    v 1: urge on with shouts; "halloo the dogs in a hunt"
    2: shout `halloo', as when greeting someone or attracting
       attention