vermilion

朱 is a pictograph of a tree with a mark painted on its trunk. Before felling a tree, the ancients would first paint a mark on the trunk for identification. Therefore, the original meaning of 朱 is the trunk or the roots exposed above the ground, and it was also used as a measure word for plants and trees. However, this sense was later taken over by the character 株. In order to make the mark easy to see, it was usually a vermilion dot. For this reason, 朱 is nowadays used only to mean vermilion color.