se·​nes·​cent si-ˈne-sᵊnt How to pronounce senescent (audio)
: relating to, characterized by, or associated with the state of being old or the process of aging : marked by or undergoing senescence
senescent foliage
The "sandwich generation"—caught between adolescent children and senescent parents …The Economist
… researchers have opened up a novel approach to combating the effects of aging with the discovery that a special category of cells, known as senescent cells, are bad actors that promote the aging of the tissues.Nicholas Wade

Word History


borrowed from Latin senēscent-, senēscens, present participle of senēscere "to grow old, age, deteriorate, slacken off, be in decline," from sen-, senex "old, aged, old man" + -ēsc-, suffix of inchoative verbs — more at senior entry 2

First Known Use

1656, in the meaning defined above

Time Traveler
The first known use of senescent was in 1656

Dictionary Entries Near senescent

Cite this Entry

“Senescent.” Dictionary, Merriam-Webster, Accessed 4 Oct. 2023.

Medical Definition


se·​nes·​cent si-ˈnes-ᵊnt How to pronounce senescent (audio)
: relating to, characterized by, undergoing, or associated with senescence
Senescent cells secrete a variety of factors but scientists still do not fully understand the role senescent cells play in many physiological processes …Science
During ageing, molecular chaperones such as heat-shock proteins are thought to combat stress-related senescent dysfunction.Marc Tatar et al., Nature

More from Merriam-Webster on senescent

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