Also called pipe organ. a musical instrument consisting of one or more sets of pipes sounded by means of compressed air, played by means of one or more keyboards, and capable of producing a wide range of musical effects.
any of various similar instruments, as a reed organ or an electronic organ.
a barrel organ or hand organ.
Biology. a grouping of tissues into a distinct structure, as a heart or kidney in animals or a leaf or stamen in plants, that performs a specialized task.