means A simple toy musical instrument that turns your humming into a buzzy, nasal drone when you sing or hum into it.

from An American coinage of the 19th century, the name almost certainly imitative of the comical buzzing sound the thing makes — though the precise path is murky. The instrument descends from the older family of 'mirlitons,' membrane-buzzers found across West Africa and Europe, where a stretched skin or paper vibrates against the player's voice. American tradition fondly credits a 19th-century inventor and an 1880s patent, but the word 'kazoo' itself seems to have grown up in the same playful, onomatopoeic soil as 'kazoo'-like nonsense syllables — a name that sounds exactly like what it does.