Source : Webster's Revised Unabridged Dictionary (1913)

Supersede \Su`per*sede"\, v. t. [imp. & p. p. {Superseded}; p.
   pr. & vb. n. {Superseding}.] [L. supersedere, supersessum, to
   sit above, be superior to, forbear, omit; super above +
   sedere to sit: cf. F. supers['e]der. See {Sit}, and cf.
   {Surcease}.]
   1. To come, or be placed, in the room of; to replace.

   2. To displace, or set aside, and put another in place of;
      as, to supersede an officer.

   3. To make void, inefficacious, or useless, by superior
      power, or by coming in the place of; to set aside; to
      render unnecessary; to suspend; to stay.

            Nothing is supposed that can supersede the known
            laws of natural motion.               --Bentley.

   4. (Old Law) To omit; to forbear.

Source : WordNet®

supersede
     v : take the place or move into the position of; "Smith replaced
         Miller as CEO after Miller left"; "the computer has
         supplanted the slide rule"; "Mary replaced Susan as the
         team's captain and the highest-ranked player in the
         school" [syn: {supplant}, {replace}, {supervene upon}]