English edit

Etymology edit

un- +‎ fail +‎ -able

Adjective edit

unfailable (comparative more unfailable, superlative most unfailable)

  1. (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?

Part or all of this entry has been imported from the 1913 edition of Webster’s Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.
(See the entry for unfailable”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.)