What term describes a board that controls several companies in one industry to eliminate competition?

The term that best describes a board that controls several companies in one industry to eliminate competition is "trust." In the context of the Industrial Revolution and subsequent economic developments, a trust refers to a group of corporations that come together under a unified board of trustees in order to manage resources and operations collectively. This arrangement allows the members to coordinate their activities, set prices, and control market supply, thereby reducing competition among themselves.

Trusts emerged as powerful entities during the late 19th and early 20th centuries, where the goal was to increase market control and maximize profits at the expense of open competition. By consolidating efforts and decision-making, trusts can stifle competition effectively, leading to higher prices and fewer choices for consumers.

While the other terms, like monopoly and cartel, are related concepts, they do not precisely fit the description given in the question. A monopoly refers to the dominance of a single company in a market, a cartel involves an agreement among competing firms to control prices and production jointly, and a syndicate generally refers to a temporary alliance formed for a specific project or purpose, which does not imply the same level of ongoing control over multiple companies or industries.