senile

[ see-nahyl, -nil, sen-ahyl ]

adjective

1. showing a decline or deterioration of physical strength or mental functioning, especially short-term memory and alertness, as a result of old age or disease.
2. of or belonging to old age or aged persons; gerontological; geriatric.
3. Physical Geography. (of topographical features) having been reduced by erosion to a featureless plain that stands everywhere at base level. Compare peneplain.

noun

1. a senile person.

senile

/ sɪˈnɪlɪtɪ; ˈsiːnaɪl /

adjective

1. of, relating to, or characteristic of old age
2. mentally or physically weak or infirm on account of old age
3. See old
   (of land forms or rivers) at an advanced stage in the cycle of erosion See old

Derived Forms

• ˈsenilely, adverb
• senility, noun

Other Words From

• un·senile adjective

Word History and Origins

Origin of senile¹

First recorded in 1655–65; from Latin senīlis “old,” from sen(ex) “old man” ( senior ) + -īlis -ile

Word History and Origins

Origin of senile¹

C17: from Latin senīlis, from senex an old man

Example Sentences

The issue is about more than just the heightened risk of a sudden death tilting the balance of power, or a senile leader making important decisions.

From Time

You realize the person's become hopelessly senile, a fact you have to forgive if you ever want to enjoy your time with them.

From The Daily Beast

The General in command of the station was a feeble old man, suffering from senile decay.

From Project Gutenberg

He bewailed the loss of his automobile that had perished of senile decay at Aix-en-Provence.

From Project Gutenberg

A sickening revolt seized him, aggravated by the smiles of the old woman, who dipped and courtesied before him in senile delight.

From Project Gutenberg

The sight of his senile weariness flashed the irony of the whole wild dream into Valmond's mind.

From Project Gutenberg

To Average Jones' inquiring gaze on this summer day it opposed the secrecy of a senile indifference.

From Project Gutenberg