What is Agistment?

Legal Definition
Agistment originally referred specifically to the proceeds of pasturage in the king's forests. To agist is, in English law, to take cattle to graze, in exchange for payment.
-- Wikipedia
Legal Definition
Contracts. The taking of another person's cattle into one's own ground to be fed, for a consideration to be paid by the owner. The person who receives the cattle is called an agister.

2. An agister is bound to ordinary diligence, and of course is responsible for loses by ordinary negligence; but he does not insure the safety of the cattle agisted. Jones, Bailm. 91; I Bell's Com. 458; Holt's N. P. Rep. 547; Story, Bail. 443; Bac. Ab. Tythes, C l.
-- Bouviers Law Dictionary
Legal Definition
The taking in of another person's cattle to be fed or to pasture, upon one's own land, in consideration of an agreed price to be paid by the owner. Also the profit or recompense for such pasturing of cattle. Bass v. Pierce, 16 Barb. (N. Y.) 595; Williams v. Miller, 68 Cal. 290, 9 Pac. 166; Auld v. Travis, 5 Colo. App. 535, 39 Pac. 357. There is also agistment of sea-banks, where lands are charged with a tribute to keep out the sea; and terrae agistatoe are lands whose owners must keep up the sea-banks. Holt-house.
-- Black's Law Dictionary
Legal Definition
The pasturing of the cattle of another on one’s land.
-- Ballentine's Law Dictionary