1. Someone who is appointed or elected to preside over an organized body of people, such as an assembly or meeting: An enormous number of presidents over the world have usually been men.
2. The chief executive of a republic: Countries that have no king or queen have a president as the head of that nation.
3. The chief executive of the United States, serving as both chief of state and chief political executive: President Donald Trump has been the administrative leader of the USA since 2016.
4. The chief officer of a branch of government, corporation, board of trustees, university, or similar organization: Mr. Smith has been the president or director of the company for many years and has been respected by all of the workers.
5. Etymology: from Latin præsidentum, præsidens, "president, governor, chosen leader of a body of people"; noun use of præsidere, "to act as head or chief"; literally, "to sit in front of"; from præ-, "before" + sedere, "to sit"