WordWeb Online

1. The branch of mechanics concerned with the forces that cause motions of bodies
   - kinetics
    
2. (music) varying loudness of sound; markings in a musical score that indicates the desired level of volume
   - dynamic

1. An efficient incentive
   "they hoped it would act as a spiritual dynamic on all churches";
   - moral force
    
2. A characteristic or manner of an interaction; a behaviour
   "Watch the dynamic between the husband and wife"; "The story is about a child who makes a friend and how the dynamic of their play evolves"

Type of: incentive, inducement, mechanics, motivator

Encyclopedia: Dynamics