Fictio
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
In Roman law. A fiction; an assumption or supposition of the law. "Fictio" in the old Roman law was properly a term of pleading, and signified a false averment on the part of the plaintiff which the defendant was not allowed to traverse; as that the plaintiff was a Roman citizen, when in truth he was a foreigner. The object of the fiction was to give the court jurisdiction.
Maine, Anc. Law, 25.