What is the meaning of organ?

noun

• A fully differentiated structural and functional unit in an animal that is specialized for some particular function.
• A government agency or instrument devoted to the performance of some specific function.
  • usage: "The Census Bureau is an organ of the Commerce Department"
• Music) an electronic simulation of a pipe organ.
  • synonyms: electric organ, electronic organ, Hammond organ
• A periodical that is published by a special interest group.
  • usage: "the organ of the communist party"
• 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.
  • synonyms: pipe organ
• A free-reed instrument in which air is forced through the reeds by bellows.
  • synonyms: harmonium, reed organ