Yaʹhoo
.A savage; a very ill-mannered person. In Gulliver’s Travels the Yahoos are described as brutes with human forms and vicious propensities. They are subject to the Houyhnhnms, or horses with human reason.
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Entry taken from Dictionary of Phrase and Fable, edited by the Rev. E. Cobham Brewer, LL.D. and revised in 1895.