inerrabilis

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.

ĭn-errābĭlis, e, adj. [2. in-erro],

unerring (post-class.): meatus, Ap. Dogm. Plat. 1, p. 7, 27: orbis, id. de Mundo, p. 58, 6: computatio, August. Civ. Dei, 21, 8.