A more thorough explanation:

Definition: A small payment made by parishioners to their rector instead of tithes. This payment could be in the form of loaves of bread or other goods.

Example: In medieval England, many people were required to pay tithes to the church. However, some parishioners were allowed to pay a maine-port instead. For example, instead of giving 10% of their crops to the church, they might give a few loaves of bread to their rector.

Explanation: The maine-port was a way for people to fulfill their obligation to the church without giving up as much of their resources. It was often used by poorer parishioners who couldn't afford to give a full tithe. The example illustrates how the maine-port worked in practice.