Senescence (noun)

1. The state or process of growing old or maturing.
2. The biological processes that lead to aging and death of a organism.

Origin:

From french sénescence, from latin senescentia, from senex ("ol.d")

Examples:

1. The study of senescence is an active area of research in the field of biology.
2. The cells in our body are programmed for senescence.
3. The leaves of the tree were showing signs of senescence.
4. The senescence of the plant is characterized by yellowing of the leaves.
5. The process of senescence is not fully understood by scientists.