con-sponsor, ōris, m.
I A joint surety , Cic. Fam. 6, 18, 2; id. Att. 12, 17.—
II One who binds or obligates himself to something ( = conjurator), acc. to Fest. p. 59, 7 Müll.
cōn-spōnsor ōris, m a joint surety. ...
An Elementary Latin Dictionary