Italian, correction, pentimento, from pentire, to repent, from Latin paenitre.
The bathysphere, resting on two pieces of lumber, was a little bigger than a wrecking ball, with three steel-rimmed portholes. Matsen gasped softly and ran his hand over its peeling, mottled surface. “Oh, man, it gets me every time,” he said. “It’s like some marvellous pentimento.”
(although really, you would have thought it'd be used in this article, which is so cool. math, art, unicorns!)