unfailable

== English == === Etymology === From un- +‎ fail +‎ -able. === Adjective === unfailable (comparative more unfailable, superlative most unfailable) (obsolete) infallible c. 1652, Joseph Hall, The Mourner in Sion (sermon) If then we believe this unfailable word of truth, who would not be content to mourn awhile, that he may rejoice for ever? Impossible to fail === References ===