1. A meeting of people in the United States, usually of a political party, with the aim of choosing a candidate for a public office in elections: "There were only seven people in the caucus who had to decide which of the candidates had the best qualifications for being governor in the next elections."
2. A limited number of influential people in an organization or political party who have the same or similar interests and want to discuss specific issues: "The caucus of the Democratic Party finally agreed on how to spend their money on the upcoming project of helping young unmarried teenage mothers."
3. Etymology: is believed to be from native American origin, "closed party meeting". It's early usage was used only in the USA until the 1870s when it appeared in British English.

Its form and meaning resembles caucauasu, "counseller" in the Algonquian languages of eastern Canada and in the USA and it was presented in print by Captain John Smith (1580-1631), an English colonist who lived in America.

1. A meeting of members of a political party for the purpose of choosing candidates for an election: A presidential caucus was recently held in Iowa.

Caucuses are planned in several states to nominate candidates for President of the United States.

2. Meetings of people; such as, members of the U.S. Congress, who meet to determine issues or to work together for certain objectives: The Congressional Education Caucus got together to see what can be done to improve the school systems in several areas of the country.

To meet together to choose candidates or to discuss special issues and to work together for political goals: Both political parties will be meeting in various states to caucus for their candidates.