Hollow

1. (of something solid) Having an empty space or cavity inside. When I broke open the shell I found it was hollow.
2. Distant, eerie; echoing, reverberating; dull, muffled; often low pitched. I heard a hollow moan.
3. Without substance; having no real or significant worth; meaningless. It was a hollow victory.
4. A small valley between mountains. He built a cabin in a hollow high up in the mountains.
5. A feeling of emptiness. When she left he had a hollow in his heart.
6. Insincere, devoid of validity. It was a hollow promise.