Pronunciation: (ôr'gun),[key] —n. 1. Also calledpipe 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.
2. any of various similar instruments, as a reed organ or an electronic organ.
3. a barrel organ or hand organ.
4. Biol.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.
6. a newspaper, magazine, or other means of communicating information, thoughts, or opinions, esp. in behalf of some organization, political group, or the like.
7. an instrument or means, as of action or performance: This committee will be the chief organ of administration. 8. Archaic. any of various musical instruments, esp. wind, instruments.