agent

Noun

• the semantic role of the animate entity that instigates or causes the happening denoted by the verb in the clause

• any agent or representative of a federal agency or bureau

• a businessman who buys or sells for another in exchange for a commission

• a substance that exerts some force or effect

• a representative who acts on behalf of other persons or organizations

• an active and efficient cause; capable of producing a certain effect
  • their research uncovered new disease agents
    

Related words

• Synonyms: 
  agentive role , federal agent , factor , broker