beneath
In a lower position, under or covered by something.
Beneath means below or underneath something. When you slide your homework beneath your textbook to keep it from blowing away, or when a cat hides beneath the bed during a thunderstorm, they're positioning themselves in the space directly under something else.
The word often carries a sense of being covered or hidden by what's above. A treasure might lie buried beneath the sand. Secrets might lurk beneath the surface of a calm lake. When you peel back the bark of a tree, you discover the living wood beneath.
Beneath can also describe something unworthy or below your standards. If someone says a task is beneath them, they mean it's too simple or degrading for someone of their ability or position. A chess champion might consider playing against a beginner beneath her skill level.
The word suggests a vertical relationship: one thing exists in a lower position relative to another. While under and below work similarly, beneath often sounds more formal or literary. You might say “the cat is under the table” in casual conversation, but write “the ancient ruins lay buried beneath centuries of earth” in a story.