undefatigable

== English == === Etymology === From un- +‎ defatigable. === Adjective === undefatigable (comparative more undefatigable, superlative most undefatigable) Obsolete form of indefatigable. 1625-1629, Abraham Darcie/Darcy and Thomas Browne (translators), The History of the Most Renowned and Victorious Princess Elizabeth, Late Queen of England (originally by William Camden) === References === “undefatigable”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.