A more thorough explanation:

NATIVI CONVENTIONARII

nativi conventionarii (pronounced nə-ti-vi kən-ven-shuh-nair-ee), noun, plural. [Law Latin] A term used in history to refer to villeins who were bound by a contract.

The term nativi conventionarii refers to a group of people who were considered villeins, or peasants who were tied to the land they worked on. However, unlike other villeins who were bound by law or custom, these villeins were bound by a contract. This means that they had agreed to work for their lord in exchange for certain rights or privileges.

One example of nativi conventionarii can be found in medieval England. In the 13th century, many villeins began to negotiate contracts with their lords in order to gain more freedom and control over their lives. These contracts often included provisions for the villein to pay a fixed rent or perform certain duties in exchange for the right to live on the lord's land.

Another example can be found in ancient Rome. During the Roman Republic, some slaves were allowed to enter into contracts with their masters in order to gain their freedom. These contracts, known as nexum, allowed the slave to pay off their debt to their master and become a free person.

These examples illustrate how nativi conventionarii were different from other villeins or slaves. They had some degree of agency and were able to negotiate the terms of their servitude. However, they were still bound to their lords or masters by a legal contract, which limited their freedom and mobility.