1. halloo - Noun
2. halloo - Verb
3. halloo - Interjection
A loud exclamation; a call to invite attention or to incite a person or an animal; a shout.
To cry out; to exclaim with a loud voice; to call to a person, as by the word halloo.
To encourage with shouts.
To chase with shouts or outcries.
To call or shout to; to hail.
An exclamation to call attention or to encourage one.
Source: Webster's dictionaryhe gave a great halloo but no one heard him Source: Internet
halloo the dogs in a hunt Source: Internet