Definition of "ineffaceable"

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.

1865, Edward Dutton Cook, Sir Felix Foy, Bart., page 233

[…] I am sure of one thing—scars are plenty enough in Germany, among the young men; and very grim ones they are, too. They crisscross the face in angry red welts, and are permanent and ineffaceable.

1880, Mark Twain [pseudonym; Samuel Langhorne Clemens], chapter VII, in A Tramp Abroad; […], Hartford, Conn.: American Publishing Company; London: Chatto & Windus