What is the meaning of contingent?

noun

• A gathering of persons representative of some larger group.
  • usage: "each nation sent a contingent of athletes to the Olympics"
• A temporary military unit.
  • usage: "the peacekeeping force includes one British contingent"
  • synonyms: detail

adjective

• Possible but not certain to occur.
  • usage: "they had to plan for contingent expenses"
• Determined by conditions or circumstances that follow.
  • usage: "arms sales contingent on the approval of congress"
  • synonyms: contingent on, contingent upon, dependent on, dependant on, dependent upon, dependant upon, depending on
• Uncertain because of uncontrollable circumstances. "the results of confession were not contingent, they were certain- George Eliot