president  
noun [ C ] uk/ˈprez.ɪ.dənt/ us/ˈprez.ɪ.dənt/
  (POLITICS)      
 A2 总统;国家主席
(the title given to) the person who has the highest political position in a country that is a republic and who, in some of these countries, is the leader of the government
  President Kennedy 肯尼迪总统 
 the president of France 法国总统 
 [ as form of address ] Thank you, Mr/Madam President. 谢谢您,总统阁下。 
 - More examples
 - Boris Yeltsin was Russia's first democratically elected president.
 - The former president has agreed to act as an intermediary between the government and the rebels.
 - The country's president is seeking to mend relations with the United States.
 - Several opposition groups are fighting to remove the president from power.
 - She is Ireland's first woman president.
 
  (ORGANIZATION)      
 (机构的)负责人,会长,主席;(尤指美国的)总裁,董事长
the person who has the highest position in an organization or, especially in the US, in a company
  a former president of the Royal Society 皇家学会的前会长 
mainly US She's a friend of the president of the bank. 她是银行总裁的朋友。 
 - More examples
 - He was president of the charity for ten years.
 - The new president of the company called a top-level management meeting.
 - The president of my bank has been named Businessperson of the Year.
 - She told me that her father is the president of a multinational corporation.
 - There was a top-level meeting of oil company presidents today to discuss the crisis.