A more thorough explanation:

Decimae vicariae (pronounced "des-i-mee vI-kair-ee-ee") is a term from Ecclesiastical law that refers to vicarage tithes. In other words, it is the right of a vicar to receive tithes from various sources, such as wool or eggs, according to need or custom. This right cannot be lost by prescription.

For example, if a farmer in a parish had a flock of sheep, the vicar of that parish would be entitled to receive a portion of the wool produced by those sheep as a tithe. Similarly, if a household in the parish kept chickens, the vicar would be entitled to a portion of the eggs produced as a tithe.

Another example would be if a parish had a mill that ground grain into flour, the vicar would be entitled to a portion of the flour produced as a tithe.

These examples illustrate how the vicar of a parish had the right to receive tithes from various sources, according to need or custom. This was an important source of income for the vicar and helped to support the work of the church in the parish.