Definition of "senescent"

And now, as the night was senescent / ⁠And star-dials pointed to morn— / ⁠As the star-dials hinted of morn— / At the end of our path a liquescent / ⁠And nebulous lustre was born

1859, Edgar Allan Poe, “Ulalume”, in The Works of the Late Edgar Allan Poe, volume 2

The history of philosophic opinion itself in interpreted by Dr. Hall in terms of a similar development, in which immature adolescent systems, staid senescent and blasé philosophies have appeared and appealed to their public in direct relation to the status of the culture-periods in which they found origin and favor.

1905 March, Joseph Jastrow, “The Natural History of Adolescence”, in Popular Science Monthly, volume 66

Put all of this together and one can envision a world two generations hence in which the richer parts of Europe and the Pacific Rim are senescent walled cities, instability and authoritarian decay predominate across much of Eurasia, and real dynamism is sustained mostly in the parts of America that are growing and building at the moment […]

2024 February 3, Ross Douthat, “Only America Can Save the Future”, in The New York Times‎

When such lines and forms of organic development prevail, the individual, as the cell of the body, becomes soon senescent, drifting inevitably into age, decay, and death.

1919, Boris Sidis, The Source and Aim of Human Progress