Meaning

noun loud confused noise from many sources

originIn early use, the noun is often mentioned as a cry by Irish people, and so is possibly borrowed from Irish; compare Irish ababú, abú (“used as a battle cry”), and Scottish Gaelic ub, ub, ubub (“used to express contempt, etc.”), ubh ubh (“used to express disgust”). The verb is derived from the noun.

Etymology from Wiktionary, CC BY-SA 3.0