se·nile (sēnīl′, sĕnīl′)
a. Relating to or having diminished cognitive function, as when memory is impaired, because of old age.
b. Being a disease or condition whose cause is primarily advanced age: senile cataracts.
2. Geology At the end of an erosion cycle: senile soil.
[Latin senīlis, proper to or characteristic of old people, aged, from senex, sen-, old; see sen- in the Appendix of Indo-European roots.]
se·nili·ty (sĭ-nĭlĭ-tē) n.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.