A more thorough explanation:

Definition: Groundage (grown-dij) is a tax or toll that was imposed on a ship that was docked in a port. The ship had to pay this tax or toll to the port authorities.

For example, if a ship was docked in a port for a week, it had to pay a groundage tax for that week. The amount of tax depended on the size of the ship and the duration of its stay in the port.

Another example is that if a ship was carrying goods, it had to pay a groundage tax on those goods. This tax was calculated based on the value of the goods and was paid to the port authorities.

These examples illustrate how groundage was a tax or toll that was levied on ships that were docked in a port. It was a way for the port authorities to generate revenue and maintain the port infrastructure.