Lewis Short
obsignātor (noun M) : id.
* A sealer, sealer up (class.): litterarum obsignator,Cic. Clu. 66, 186.—Esp., the witnesses who set their seals to a will, Cic. Clu. 13, 37: testamenti,id. Att. 12 18, b, 2: decisionis,id. Fl. 36, 89.
Charlton T. Lewis, Charles Short, A Latin Dictionary