Apoptosis

n. programmed cell death, natural process in which a cell disintegrates after reaching a certain age or due to poor cell health

Apoptosis (pronounced ă-pŏp-tŏ’sĭs, apo tō' sis) is a form of programmed cell death in multicellular organisms. It is one of the main types of programmed cell death (PCD), and involves an orchestrated series of biochemical events leading to a characteristic cell morphology and death. It involves an orchestrated series of biochemical events which lead to a variety of morphological changes, including blebbing, changes to the cell membrane such as loss of membrane asymmetry and attachment, cell shrinkage, nuclear fragmentation, chromatin condensation and chromosomal DNA fragmentation (1-4). The apoptotic process is executed in such a way as to safely dispose of cellular debris.
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Noun
1. a type of cell death in which the cell uses specialized cellular machinery to kill itself; a cell suicide mechanism that enables metazoans to control cell number and eliminate cells that threaten the animal's survival
(synonym) programmed cell death, caspase-mediated cell death
(hypernym) necrobiosis, cell death

[AY-pup-TOE-siss]
A type of cell death in which a series of molecular steps in a cell leads to its death. This is the body's normal way of getting rid of unneeded or abnormal cells. The process of apoptosis may be blocked in cancer cells. Also called programmed cell death. 

The genetically programmed death of cells at specific times during embryogenesis, metamorphosis, and during cell turnover in adults.