This week, Democrat members in Iowa met to choose their presidential nominee, but the headlines the next day were all about the “Iowa caucus shambles”. Everyone was talking knowledgably about caucuses, even if they didn’t quite know what one was.

The word is first recorded in 18th-century Boston as the name for a private political club. Where it came from is unclear: some point to the rare Latin “caucus” meaning drinking vessel, while others say it adapts a Native American word for wise elders. In US electoral politics, a “caucus” differs from a primary in that the former requires party members to meet and debate their choice before voting.

A “caucus” can also be any group that meets to discuss particular subjects, thus the Congressional Black Caucus and also the dubiously named House Freedom Caucus, packed with libertarian eccentrics. In British English, “caucus” has sometimes had a more pejorative meaning of a group that plots in secret, of which we enjoy no little variety of modern examples. Indeed, the original caucus clubs were supposedly meetings of the rich and powerful to fix elections, so in that sense caucuses today are not confined to America alone.