悬针垂露/ 懸針垂露 xuánzhēnchuílù (also xuánzhēnchuílòu) two vertical stroke styles
A calligraphy term referring to the two main ways to write a vertical stroke: 悬针 xuánzhēn where the tip is tapered to a sharp point, and 垂露 chuílù where the tip is rounded like a water droplet.