To sequester means to isolate or set something apart from everything else, keeping it separate and often hidden away. When a jury is sequestered during an important trial, the members stay in a hotel away from their families, can't watch the news, and can't use their phones. This happens so outside information won't influence their decision.

You might sequester yourself in your room to focus on a difficult project, shutting the door and turning off distractions. A scientist might sequester a chemical sample in a sealed container to prevent contamination. The word suggests deliberate separation for a specific purpose.

In nature, trees sequester carbon dioxide from the air, essentially capturing and storing it in their wood and roots. This environmental meaning has become important as people look for ways to remove greenhouse gases from the atmosphere.

The related word sequestered describes something tucked away or isolated: a sequestered cabin in the mountains sits far from civilization, peaceful and remote. When something is sequestered, it's separated in a way that protects or preserves it, like a garden hidden behind high walls.