Organ

1. (music) an electronic simulation of a pipe organ. Organ music is often heard in big churches.
2. 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. She was an excellent player of the organ.
3. An agency dedicated tot he performance of specified functions. The FBI is an organ of the Justice Department.
4. In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. The heart, stomach and other organs functioning well are vital to your good health.