obreptīvus — Lewis & Short
obreptīvus, a, um, adj.obrepo,
I secret, clandestine (post-class.):
supplicatio,Symm. Ep. 5, 64; Cod. Th. 16, 10, 8.—Hence, adv.: obreptīvē, surreptitiously, clandestinely (post-class.): aut clanculo supplicare, Cod. Th. 16, 1, 4 fin.