If we are being really pedantic, a Dutch oven is a type of pot used for cooking on open fire. They used to have little legs built on so you could place it over some coals. The lid would be flat so you could put coals on top of it. That way you could use it as an actual oven to bake bread or whatever on a wood fire.

Modern people don’t cook much on wood fires, but in the US, we still generally call any big cast iron pot a “Dutch oven”.