senile

Senile is an adjective meaning “of or relating to old age” and derives from the Latin senilis, from senex meaning “old man.” In older English usage it described traits associated with aging. In medical literature, the term was historically used to denote cognitive decline attributed to aging or to describe dementia that appeared primarily in older individuals, as in “senile dementia.”

Modern usage has shifted away from “senile” in favor of precise diagnoses. “Senile dementia” is now considered outdated or imprecise; clinicians differentiate Alzheimer’s disease, other specific dementias (vascular dementia, Lewy body dementia, frontotemporal dementia), and non-pathological age-related cognitive decline. The phrase “senile plaques” also appears in older neuroscience texts but is less preferred today; current terminology emphasizes specific neuropathology such as amyloid plaques and neuritic plaques within defined disease contexts.

Because the term can be stigmatizing, contemporary guidelines discourage using “senile” when describing people and encourage person-first language or precise medical diagnoses. In biological contexts, “senescence” refers to the process of aging at the cellular or organismal level, not a disease. See also dementia, aging, senescence, and Alzheimer’s disease.