Per
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Lat. By. When a writ of entry Is sued out against the alienee of the original intruder or disseisor or against his heir to whom the land has descended, it is said to be brought "in the per," because the writ then states that the tenant had not'entry but by (per) the original wrong-doer.
3 BL Comm. 181.