The Collaborative International Dictionary of English v.0.48:
Heriot \Her"i*ot\, n. [AS. heregeatu military equipment, heriot;
here army + geatwe, pl., arms, equipments.] (Eng. Law)
Formerly, a payment or tribute of arms or military
accouterments, or the best beast, or chattel, due to the lord
on the death of a tenant; in modern use, a customary tribute
of goods or chattels to the lord of the fee, paid on the
decease of a tenant. --Blackstone. Bouvier.
Heriot custom, a heriot depending on usage.
Heriot service (Law), a heriot due by reservation in a
grant or lease of lands. --Spelman. Blackstone.