buried secret

A buried secret is something hidden from others, often deliberately concealed because revealing it would cause harm, embarrassment, or disruption.

The metaphor suggests something interred underground—out of sight but still existing, potentially exhumed.

Buried secrets tend to involve past misdeeds, family scandals, or uncomfortable truths: The investigation uncovered buried secrets about the company's early investors.

Unlike a mere secret, a buried one implies active effort to keep it hidden, often for years.