Sequester: 1. In medicine, to set apart, detach or separate a small portion of tissue from the rest. May be naturally occurring or iatrogenic. 2. In bone, for a piece of dead bone to separate from the sound bone. 3. In biochemistry, to isolate a constituent of a system by chelation or other means.
From the French sequester, from the late Latin sequestrare, meaning to place in safe keeping.