[ see-nahyl, -nil, sen-ahyl ]
/ ˈsi naɪl, -nɪl, ˈsɛn aɪl /


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.
of or belonging to old age or aged persons; gerontological; geriatric.
Physical Geography. (of topographical features) having been reduced by erosion to a featureless plain that stands everywhere at base level.Compare peneplain.


a senile person.

Origin of senile

1655–65; < Latin senīlis old, equivalent to sen(ex) old man (akin to senior) + -īlis -ile


un·se·nile, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for senile

British Dictionary definitions for senile

/ (ˈsiːnaɪl) /


of, relating to, or characteristic of old age
mentally or physically weak or infirm on account of old age
(of land forms or rivers) at an advanced stage in the cycle of erosionSee old (def. 18)

Derived forms of senile

senilely, adverbsenility (sɪˈnɪlɪtɪ), noun

Word Origin for senile

C17: from Latin senīlis, from senex an old man
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for senile

[ sēnīl′, sĕnīl′ ]


Relating to, characteristic of, or resulting from old age.
Exhibiting the symptoms of senility, as impaired memory or the inability to perform certain mental tasks.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.