yahoo (Noun) — A person who is not very intelligent or interested in culture.
yahoo (Noun) — A widely used search engine for the web that finds information, news, images, products, finance.
yahoo (Noun) — One of a race of brutes resembling men but subject to the Houyhnhnms in a novel by Jonathan Swift.
yahoo (Interjection) — Exclamation of joy or victory. ex. "They learn new things and they have a good time, yahoo!"