The Collaborative International Dictionary of English v.0.48:
Vis \Vis\, n.
1. Force; power.
(a) Physical force.
(b) Moral power.
Principle of vis viva (Mech.), the principle that the
difference between the aggregate work of the accelerating
forces of a system and that of the retarding forces is
equal to one half the vis viva accumulated or lost in the
system while the work is being done.
Vis impressa [L.] (Mech.), force exerted, as in moving a
body, or changing the direction of its motion; impressed
Vis inertiae. [L.]
(a) The resistance of matter, as when a body at rest is
set in motion, or a body in motion is brought to rest,
or has its motion changed, either in direction or in
(b) Inertness; inactivity.
Note: Vis intertiae and inertia are not strictly synonymous.
The former implies the resistance itself which is
given, while the latter implies merely the property by
which it is given.
Vis mortua [L.] (Mech.), dead force; force doing no active
work, but only producing pressure.
Vis vitae, or Vis vitalis [L.] (Physiol.), vital force.
Vis viva [L.] (Mech.), living force; the force of a body
moving against resistance, or doing work, in distinction
from vis mortua, or dead force; the kinetic energy of a
moving body; the capacity of a moving body to do work by
reason of its being in motion. See Kinetic energy, in
the Note under Energy. The term vis viva is not usually
understood to include that part of the kinetic energy of
the body which is due to the vibrations of its molecules.