1. the quality or state of being hidden, concealed, or not visible
2. the condition of being kept secret or unknown

Examples

• The hiddenness of the treasure made the search more challenging.
• She appreciated the hiddenness of the garden, which offered privacy from the street.
• The hiddenness of his true feelings became apparent only after years of friendship.
• The document's hiddenness was maintained through careful archival practices.
• Despite the hiddenness of the cave entrance, explorers eventually discovered it.
• The hiddenness of the problem meant it went undetected for months.