1.a fully differentiated structural and functional unit in an animal that is specialized for some particular function
2.a government agency or instrument devoted to the performance of some specific function;
The Census Bureau is an organ of the Commerce Department
3.(music) an electronic simulation of a pipe organ
4.a periodical that is published by a special interest group;
the organ of the communist party
5.wind instrument whose sound is produced by means of pipes arranged in sets supplied with air from a bellows and controlled from a large complex musical keyboard
6.a free-reed instrument in which air is forced through the reeds by bellows