underlayer

The carpet has a thick underlayer that keeps the floor warm.

用法提示：此处 underlayer 是名词，指位于另一层下方的层。

Painters often apply an underlayer before the final coat.

用法提示：underlayer 作名词，表示涂在表层之下的底层。

The archaeologists found an underlayer of clay beneath the stone floor.

用法提示：underlayer 是名词，意为“下层、底层”。