sill

Definition

A flat horizontal piece at the bottom of a door or window; also, in geology, a sheet of igneous rock that has intruded between older rock layers.

日本語 ドアまたは窓の下の平らな水平部分、または岩石学では、古い岩層の間で侵入した igneous 岩のシート

Example

"He wiped his boots on the doorstep before stepping over the sill."