<p><strong>Noun</strong></p><ul><li>(Used with a singular verb) Physics. The branch of mechanics that deals with the motion and equilibrium of systems under the action of forces.</li><li>(Used with a plural verb) The motivating or driving forces, physical or moral, in any field.</li><li>(Used with a plural verb) The pattern or history of growth, change, and development in any field.</li><li>(Used with a plural verb) Variation and gradation in the volume of musical sound.</li><li>(Used with a singular verb) Psychodynamics.</li></ul>