1695. Congreve, Love for L., IV. xii. Ill stars, and unconvertible ignorance attend him!
1805. Ann. Rev., III. 622. The Mohammedans have been found unconvertible for this plain reason.
1864. Bowen, Logic, v. 139. Unconvertible are A and B.
Hence Unconvertibility.
1804. Southey, Lett. (1856), I. 285. That the common opinion of the unconvertibility of this people is ill-founded.