n. pl. mor·tal·i·ties
1. The quality or condition of being mortal.
2. Mortals considered as a group; the human race.
3. Death, especially of large numbers; heavy loss of life: the mortality wrought by an epidemic.
4. Death rate.
5. The rate of failure or loss: the high mortality among family-run farms.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. 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.