Petitio
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Lat. In the civil law. The plaintiff's statement of his cause of action in an action in rem.
Calvin.
In old English law
Petition or demand; the count in a real action; the form of words in which a title to land was stated by the demandant, and which commenced with the word "veto."
1 Reeve, Eng. Law, 176.