The Collaborative International Dictionary of English v.0.48:

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 & p. p. Superseded; p.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.
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   2. To displace, or set aside, and put another in place of;
      as, to supersede an officer.
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   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.
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            Nothing is supposed that can supersede the known
            laws of natural motion.               --Bentley.
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   4. (Old Law) To omit; to forbear.
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Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "superseded":
   abandoned, abjured, antiquated, antique, archaic, dead, deserted,
   discontinued, disused, done with, extinct, not worth saving,
   obsolescent, obsolete, old, old-fashioned, on the shelf, out,
   out of use, out-of-date, outdated, outmoded, outworn, passe,
   past use, pensioned off, relinquished, renounced, resigned,
   retired, superannuate, superannuated, worn-out