dynamics

noun[plural only]5

1. •
   Forces that stimulate growth, change, or development.

   • The changing dynamics in international politics led to such an outcome.
2. •
   The branch of mechanics that is concerned with the effects of forces on the motion of objects.
3. •
   Loudness of sound.
4. •
   The changing amplitude or level of a sound wave or selection of audio.
5. •
   The volume with which music is to be performed, denoted by such terms as piano, mezzo piano, mezzo forte, or forte.