hollow

A small valley between mountains.

He built himself a cabin in a hollow high up in the Rockies.

c. 1710–20, Matthew Prior, The First Hymn Of Callimachus: To Jupiter Forests grew upon the barren hollows.

A sunken area on a surface.

the hollow of the hand

An unfilled space in something solid; a cavity, natural or artificial.

a hollow in a tree trunk

A feeling of emptiness.

a hollow in the pit of one’s stomach

to make a hole in something; to excavate

Having an empty space or cavity inside.

a hollow tree; a hollow sphere

Distant, eerie; echoing, reverberating, as if in a hollow space; dull, muffled; often low-pitched.

He let out a hollow moan.

Through thy battlements, Newstead, the hollow winds whistle:

Without substance; having no real or significant worth; meaningless.

a hollow victory

Insincere, devoid of validity; specious.

a hollow promise

"Hey, if anything happens to that, my ass is grass," Y.T. says. She's trying to sound tough and brave, but it's a hollow act in these circumstances.

Concave; gaunt; sunken.

To view with hollow eye and wrinkled brow