Word Origin & History
boo
"to startle," c.1430, probably because it can be pronounced as a loud, booming sound; as an expression of disapproval, 1816, perhaps imitative of oxen; hence, the verb meaning "shower someone with boos" (1893). Boo-hoo first recorded 1525, originally of laughter or weeping. To say boo "open one's mouth, speak," originally was to say boo to a goose.