Definition from Wiktionary, the free dictionary
thumbhole (plural thumbholes)
- A hole designed to receive a thumb.
2007 January 7, David Colman, “It’s Like Nothing, Really”, in New York Times:
- The paint set is the top-of-the-line model, the Extra-Fine Oil Artist’s Box with a 39-tube spectrum of colors, 6 different painting mediums, 10 brushes (5 sable and 5 hog bristle), palette knives and a palette (with old-fashioned thumbholes), all in a portable walnut box.