What is Avenage?

Legal Definition
In law, avenage was the payment of a certain quantity of oats to a landlord, in lieu of some other duties; or, as a rent, from the tenant. The word is French, formed of the Latin, avena, oats.
-- Wikipedia
Legal Definition
A certain quantity of oats paid by a tenant to his landlord as rent or in lieu of some other duties.
-- Black's Law Dictionary