Propulsion is the generation of force by any combination of pushing or
pulling to modify the translational motion of an object, which is typically a
rigid body (or an articulated rigid body) but may also concern a fluid. The
term is derived from two Latin words: pro , meaning before or forward ;
and pellere , meaning to drive. A propulsion system consists of a
source of mechanical power, and a propulsor (means of converting this power
into propulsive force).
Plucking a guitar string to induce a vibratory translation is technically a
form of propulsion of the guitar string; this is not commonly depicted in this
vocabulary, even though human muscles are considered to propel the fingertips.