The Collaborative International Dictionary of English v.0.48:

Constituent \Con*stit"u*ent\ (k[o^]n*st[i^]t"[-u]*[-e]nt), a.
   [L. constituens, -entis, p. pr. See Constitute.]
   1. Serving to form, compose, or make up; elemental;
      component.
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            Body, soul, and reason are the three parts
            necessarily constituent of a man.     --Dryden.
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   2. Having the power of electing or appointing.
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            A question of right arises between the constituent
            and representative body.              --Junius.
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The Collaborative International Dictionary of English v.0.48:

Constituent \Con*stit"u*ent\, n.
   1. The person or thing which constitutes, determines, or
      constructs.
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            Their first composure and origination require a
            higher and nobler constituent than chance. --Sir M.
                                                  Hale
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   2. That which constitutes or composes, as a part, or an
      essential part; a component; an element.
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            We know how to bring these constituents together,
            and to cause them to form water.      --Tyndall.
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   3. One for whom another acts; especially, one who is
      represented by another in a legislative assembly; --
      correlative to representative.
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            The electors in the district of a representative in
            Congress, or in the legislature of a State, are
            termed his constituents.              --Abbot.
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            To appeal from the representatives to the
            constituents.                         --Macaulay.
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   4. (Law) A person who appoints another to act for him as
      attorney in fact. --Burrill.
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WordNet (r) 3.0 (2006):

constituent
    adj 1: constitutional in the structure of something (especially
           your physical makeup) [syn: constituent(a),
           constitutional, constitutive(a), organic]
    n 1: an artifact that is one of the individual parts of which a
         composite entity is made up; especially a part that can be
         separated from or attached to a system; "spare components
         for cars"; "a component or constituent element of a system"
         [syn: component, constituent, element]
    2: a member of a constituency; a citizen who is represented in a
       government by officials for whom he or she votes; "needs
       continued support by constituents to be re-elected"
    3: something determined in relation to something that includes
       it; "he wanted to feel a part of something bigger than
       himself"; "I read a portion of the manuscript"; "the smaller
       component is hard to reach"; "the animal constituent of
       plankton" [syn: part, portion, component part,
       component, constituent]
    4: (grammar) a word or phrase or clause forming part of a larger
       grammatical construction [syn: constituent, grammatical
       constituent]
    5: an abstract part of something; "jealousy was a component of
       his character"; "two constituents of a musical composition
       are melody and harmony"; "the grammatical elements of a
       sentence"; "a key factor in her success"; "humor: an
       effective ingredient of a speech" [syn: component,
       constituent, element, factor, ingredient]