Stable equilibrium

Stable \Sta"ble\ (st[=a]"b'l), a. [OF. estable, F. stable, fr.
   L. stabilis, fr. stare to stand. See {Stand}, v. i. and cf.
   {Establish}.]
   1. Firmly established; not easily moved, shaken, or
      overthrown; fixed; as, a stable government.
      [1913 Webster]

            In this region of chance, . . . where nothing is
            stable.                               --Rogers.
      [1913 Webster]

   2. Steady in purpose; constant; firm in resolution; not
      easily diverted from a purpose; not fickle or wavering;
      as, a man of stable character.
      [1913 Webster]

            And to her husband ever meek and stable. --Chaucer.
      [1913 Webster]

   3. Durable; not subject to overthrow or change; firm; as, a
      stable foundation; a stable position.
      [1913 Webster]

   4. (Physics) So placed as to resist forces tending to cause
      motion; of such structure as to resist distortion or
      molecular or chemical disturbance; -- said of any body or
      substance.
      [Webster 1913 Suppl.]

   {Stable equilibrium} (Mech.), the kind of equilibrium of a
      body so placed that if disturbed it returns to its former
      position, as in the case when the center of gravity is
      below the point or axis of support; -- opposed to
      {unstable equilibrium}, in which the body if disturbed
      does not tend to return to its former position, but to
      move farther away from it, as in the case of a body
      supported at a point below the center of gravity. Cf.
      {Neutral equilibrium}, under {Neutral}.
      [1913 Webster]

   Syn: Fixed; steady; constant; abiding; strong; durable; firm.
        [1913 Webster]