Definition of: halloo

(hə·l′) interj.
1. An exclamation to attract attention, express surprise, etc.
2. A shout to incite hounds to the chase.
—noun A cry of “halloo.”
—v.i. To shout “halloo”; cry out.
—v.t.
1. To incite or encourage with shouts.
2. To shout to; hail.
3. To shout (something). Also hal·lo, hal·loa (hə·lō): also spelled holla, hollo, holloa, hillo, hilloa, hullo. [<OF halloer pursue noisily]