n.[C]

1. 【建】基石，底木
2. 门槛；窗台
   She sat with one elbow resting on the sill of the open window.

   她坐在那儿，一只胳膊肘搁在开着窗的窗台上。

3. 【地】岩床；海底山脊

n.

1. a shelf or slab of stone, wood, or metal at the foot of a window or doorway.
   ▸a strong horizontal member at the base of any structure, e.g. in the frame of a motor or rail vehicle.
2. Geology  a tabular sheet of igneous rock intruded between and parallel with the existing strata. Compare with dyke¹.
3. an underwater ridge or rock ledge extending across the bed of a body of water.