Lewis & Short

persuāsĭbĭlis, e, adj. [persuadeo], convincing, persuasive (post-Aug.): rhetorice est vis inveniendi omnia in oratione persuasibilia, Quint. 2, 15, 13; so id. 2, 15, 17: humanae sapientiae verba, Vulg. 1 Cor. 2, 4; Hier. Ep. 65, 9.
In sing.: persuasibile, Quint. 2, 15, §§ 16 and 21.
Adv.: persuā-sĭbĭlĭter, convincingly, persuasively: dicere, Cels. ap. Quint. 2, 15, 14; 22.