tē̆trarchĭa, ae, f., = τετραρχία,
the dominions of a tetrarch , a tetrarchy , Cic. Deiot. 15, 42; id. Div. 1, 15, 27; Auct. B. Alex. 78, 3.
tetrarchia ae, f , τετραρχία, a district governed by a tetrarch, tetrarchy. ...
An Elementary Latin Dictionary