A yahoo is a loud, rowdy boor with no manners. A bunch of yahoos, some yahoo shouting, yahoos in the street.
Swift invented the word in Gulliver's Travels for a race of filthy brutes who look human, and his point was that they are us. The internet company took the name deliberately. As an exclamation, yahoo is a separate word made from a shout of delight.
1nounyahooA loud, rowdy person with no manners.
“A group of drunken yahoos was shouting and throwing chips at passers-by.”
yahoo is a person.
YAhoo → what GULLIVER found running wild
In Gulliver's Travels the Yahoos are wild and dirty, barely better than animals. A yahoo is still loud and has no manners, exactly like them.
Coined by Jonathan Swift in Gulliver's Travels in 1726 as the name of a race of human-like brutes.
From Gulliver's Travels by Jonathan Swift, where Yahoo is the name of a race of brutes.
Etymology from Wiktionary, CC BY-SA