Avercorn
A New Law Dictionary and Glossary · Alexander M. Burrill · 1850
A New Law Dictionary and Glossary
[from Fr. ouvre, or ouvrage, work, according to Somner; or from avoir, to have or receive, according to Cowell.] In old English law. A reserved rent in corn, [grain,] paid to religious houses by their farmers or tenants.
Cowell.
Corn drawn to the lord's granary by the working cattle (averiis) of the tenant. Somner's Lex. cited ibid.