constituent

noun
  1. A component or part of something, especially a part of a system or mixture. noun
    Water is a major constituent of the human body.
    The constituents of the alloy include copper and zinc.
  2. A person who authorizes another to act on their behalf, especially a voter who elects a representative. noun
    The senator met with her constituents to discuss their concerns.
    As a constituent, he felt it was important to voice his opinions to his local representative.
  3. Being a part of a whole; serving to compose or make up something. adjective
    The constituent elements of the compound were carefully measured.
    Each constituent part of the machine was inspected for defects.