a toy musical instrument consisting of a small, open tube with a top hole covered by a membrane, as of paper, that vibrates to give a buzzing quality to tones hummed through the tube
See kazoo in American Heritage Dictionary 4
(kə-zo͞oˈ)
nounpl.ka·zoos
A toy musical instrument with a membrane that produces a buzzing sound when a player hums or sings into the mouthpiece.