垂线

(math.) perpendicular line / vertical line

to hang (down) / droop / dangle / bend down / hand down / bequeath / nearly / almost / to approach

variant of 線|线[xian4]

thread / string / wire / line / CL:條|条[tiao2],股[gu3],根[gen1] / (after a number) tier (unofficial ranking of a Chinese city)

plumbline