A more thorough explanation:

Mercatum is a legal term that refers to a market, a contract of sale, or a bargain. It is used to describe a place where goods are bought and sold, or an agreement between two parties to exchange goods or services for money.

• When you go to the grocery store, you are participating in a mercatum. You are buying goods (food) in exchange for money.
• If you sell your old bike to a friend for $50, you are making a mercatum. You are entering into a contract of sale, where you agree to exchange your bike for your friend's money.
• When a company hires an employee, they are making a mercatum. The company agrees to pay the employee a certain amount of money in exchange for their work.

These examples illustrate how mercatum can refer to both physical places (like a grocery store) and agreements between people (like a contract of sale or employment). It is a term that is often used in legal contexts to describe transactions and agreements.