A more thorough explanation:

Mora is a legal term that refers to a willful delay or default in fulfilling a legal obligation. This means that if someone owes money or has a duty to perform a task, but they intentionally delay or fail to do so, they are in mora. For example, if someone borrows money from a bank and doesn't make their payments on time, they are in mora.

Under Roman law, a creditor or debtor in mora could be required to pay interest on any money owed. This means that if someone is in mora, they may have to pay extra money as a penalty for their delay or default.

It's important to note that mora usually applies to a debtor, but it can also apply to a creditor who fails to accept performance duly tendered. This means that if someone owes money to another person, but that person refuses to accept payment, they could be in mora.

In historical usage, mora could also refer to unprofitable ground, such as a moor.

• If a tenant fails to pay their rent on time, they are in mora.
• If a contractor doesn't complete a project by the agreed-upon deadline, they are in mora.
• If a borrower doesn't make their loan payments on time, they are in mora.

These examples illustrate how someone can be in mora if they intentionally delay or fail to fulfill a legal obligation, such as paying rent, completing a project, or making loan payments. In each case, the person in mora may be required to pay extra money as a penalty for their delay or default.