Glossary of Terms:
 
key
1) The mechanical device which triggers a note on a keyboard.
2) The key (pitch) center of a song; indicated on sheet music by the amount of sharps (#) or flats (b) in the key signature.
3) The control of a dynamics processing device by an external audio signal.
4) A button on a computer keyboard.
Source: Recording Institute of Detroit

Also refered as:
  key center   note   trigger