A more thorough explanation:

Definition: Marshalsea was a court or seat of the marshal of the royal household. It was also a debtor's prison in London under the jurisdiction of the Court of Marshalsea.

Example: In the 18th century, the Marshalsea prison was notorious for its harsh conditions and overcrowding. Many debtors were imprisoned there, including Charles Dickens' father, who inspired his novel "Little Dorrit."

Explanation: The example illustrates how Marshalsea was a debtor's prison in London where people who couldn't pay their debts were imprisoned. The conditions were often terrible, and many people suffered there. Charles Dickens' father was one of the prisoners, and his experience inspired his son's novel about life in the Marshalsea prison.