nail
Quick Summary
The "nail" was an ancient and medieval unit of length, primarily used for measuring cloth. It was equivalent to 1/16 of a yard, or 2.25 inches (5.7 cm). This measurement ultimately derived from the Roman digitus.1
The nail was also defined as half a finger, representing the length from the tip of the middle finger to the center of the second joint from the tip. Consequently, a finger's length became double the nail's length. While Leonardo da Vinci used a "finger" measurement, his was actually a finger's breadth, measuring 0.75 inches.1
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.