Harmonic motion can mean: the displacement of the particle executing oscillatory motion that can be expressed in terms of sine or cosine functions known as harmonic motion.
The motion of a Harmonic oscillator (in physics), which can be: Simple harmonic motion Complex harmonic motion Keplers laws of planetary motion (in physics, known as the harmonic law) Quasi-harmonic motion Musica universalis (in medieval astronomy, the music of the spheres) Chord progression (in music, harmonic progression)
See also Pendulum Harmonograph Circular motion