meeting (an occasion when people come together to discuss things and make decisions): We held an urgent meeting to discuss the problem.
gathering (an occasion when a group of people come together for a particular purpose): The president addressed a gathering of political leaders. We’re having a small family gathering this weekend.
conference (a formal meeting in which people with the same job or interests come together to discuss their views): They attended a three-day conference on the environment.
summit (a conference between leaders or highest-level officials): World leaders will attend the economic summit next week.
session (a formal meeting of a court, parliament, etc.): The UN Security Council has called an emergency session to discuss the crisis.
convention (a large conference of the members of a profession, a political party, etc.): They are holding their party convention in Paris.
rally (a large public meeting to support or protest against someone or something): Thousands of people attended a rally calling for peace.
