(1):

(n.) A long, slender rope made of hemp or strips of hide, esp. one with a noose; - used as a lasso for catching cattle, horses, etc., and for picketing a horse so that he can graze without wandering.

(2):

(v. t.) To secure with a lariat fastened to a stake, as a horse or mule for grazing; also, to lasso or catch with a lariat.