ineffaceable

in- +‎ effaceable

ineffaceable (comparative more ineffaceable, superlative most ineffaceable)

1. Incapable of being effaced.
   • 1865, Edward Dutton Cook, Sir Felix Foy, Bart. (page 233)

     Mr. Disbrowe was reclining on a well-worn horsehair-covered sofa, his frequent reclinings on which piece of furniture had stamped a deep and quite ineffaceable impression of his weighty form upon the cushion.