agent 
/ˈeɪʤənt/ noun
plural agents /ˈeɪʤənt/ noun [count] 1 : a person who does business for another person : a person who acts on behalf of another
▪ They worked with a travel agent to plan their vacation. ▪ The actor got a starring role through his (theatrical) agent. ▪ a literary agent [=a person who helps writers to get their works published] — see also free agent, insurance agent, press agent, real estate agent 2 : a person who tries to get secret information about another country, government, etc. : spy, secret agent
▪ a government agent — see also double agent, special agent 3 : a person or thing that causes something to happen
▪ They view themselves as agents of social change. [=people who cause social change to happen] 4 : something (such as a chemical) that is used to produce a particular effect or result
▪ The drug is an effective agent for the treatment of asthma. ▪ the main flavoring agent in the drink ▪ Cornstarch is used as a thickening agent in sauces.
▪ They worked with a travel agent to plan their vacation. ▪ The actor got a starring role through his (theatrical) agent. ▪ a literary agent [=a person who helps writers to get their works published] — see also free agent, insurance agent, press agent, real estate agent
▪ a government agent — see also double agent, special agent
▪ They view themselves as agents of social change. [=people who cause social change to happen]
▪ The drug is an effective agent for the treatment of asthma. ▪ the main flavoring agent in the drink ▪ Cornstarch is used as a thickening agent in sauces.
