Cork
Stopper, Plug
noun
せん
千 (せん) Thousand
線 (せん) Line
栓 (せん) Cork, Stopper, Plug
栓抜き (せんぬき) Bottle Opener, Corkscrew
柱 (はしら) Pillar
Yuri says 栓 can also be a Stopper or Plug for a sink or bathtub.