senescencenoun [ U ]
/sɪˈnes.əns//sɪˈnes.əns/specializedthe fact of becoming older, and therefore being in less good condition and less able to function well:
Senescence refers to gradual deterioration with age and in animals is typically very obvious under zoo conditions.
senescent
adjective /sɪˈnes.ənt//sɪˈnes.ənt/
senescent cells