(derogatory) A rough, coarse, loud or uncouth individual.
(cryptozoology) A humanoid cryptid said to exist in parts of eastern Australia, and also reported in the Bahamas.
1835, James Holman, Travels, quoted by Malcolm Smith, Bunyips and Bigfoots (Millennium Books, 1996, →ISBN), who notes that the Australian sense almost certainly derives from Gulliver's Travels, despite Holman's report
The natives are greatly terrrified by the sight of a person in a mask calling him "devil" or Yah-hoo, which signifies evil spirit.
interjection
An exclamation of joy or enjoyment.
A battle cry.
verb
(transitive, intransitive, informal) To give a cry of yahoo.