Glossary of Terms:
 
key center
Indicated on sheet music by the key signature, the key center (or key) is based on the first note of the musical scale a song is based on. While not necessarily the first or last note of a song, the key center is usually a pitch heard throughout the song, and also gives the song finality or a feeling of closure.
Source: Yamaha

Also refered as:
  key
Related terms:
  key signature   note   pitch