Pentimento

pentimento \ˌpen-tə-ˈmen-(ˌ)tō\ noun: a reappearance in a painting of a design which has been painted over

Etymology: Italian, literally, repentance, correction, from pentire to repent, from Latin paenitēre to cause regret, feel regret, perhaps from paene almost

I had always thought that an example of pentimento in a painting was the emergence of, say, the pattern from a colored, tiled floor through a foreground figure because of the gradual, increased transparency of paint layers over the years, evidence that the artist purposefully painted the entire floor first before painting the figure on top of it.

But according to Wikipedia, pentimento is “an alteration in a painting, evidenced by traces of previous work, showing that the artist has changed his mind as to the composition during the process of painting.” So careful visual inspection might show traces that a hand originally had been drawn in a slightly different position, or X-rays might reveal that the underdrawing of a foot places it at a different angle than the final painted foot.

Wikipedia’s definition makes more sense in relation to pentimento’s etymology: “to repent.” An artist regrets his first decision, so he changes it for the final version.