\Sub`sti*tu"tion\, n. [L. substitutio: cf. F.
substitution.]
1. The act of substituting or putting one person or thing in
   the place of another; as, the substitution of an agent,
   attorney, or representative to act for one in his absense;
   the substitution of bank notes for gold and silver as a
   circulating medium.
2. The state of being substituted for another.
3. The office or authority of one acting for another;
   delegated authority. [R.] --Shak.
4. (Civil Law) The designation of a person in a will to take
   a devise or legacy, either on failure of a former devisee
   or legatee by incapacity or unwillingness to accept, or
   after him. --Burrill.
5. (Theol.) The doctrine that Christ suffered vicariously,
   being substituted for the sinner, and that his sufferings
   were expiatory.
6. (Chem.)The act or process of substituting an atom or
   radical for another atom or radical; metethesis; also, the
   state of being so substituted. See {Metathesis}.