–noun, plural -ties.
1. the state or condition of being subject to death; mortal character, nature, or existence.
2. the relative frequency of deaths in a specific population; death rate.
3. mortal beings collectively; humanity.
4. death or destruction on a large scale, as from war, plague, or famine.
5. Obsolete . death.
1300–50; ME mortalite < MF < L mortālitās. See mortal, -ity
— n , pl -ties
1. the condition of being mortal
2. great loss of life, as in war or disaster
3. the number of deaths in a given period
4. mankind; humanity
5. an obsolete word for death
Collins English Dictionary - Complete & Unabridged 10th Edition
mid-14c., "condition of being mortal," from Fr. mortalité (12c.), from L. mortalitem , from mortalis (see mortal). Meaning "widespread death" is from c.1400; meaning "number of deaths from some cause or in a given period" is from 1640s.
Online Etymology Dictionary, © 2010 Douglas Harper
pl -ties ; 1 : the quality or state of being mortal
2 a : the number of deaths in a given time or place
b : the proportion of deaths to population : DEATH RATE called also mortality rate compare FERTILITY 2 , MORBIDITY 2 ,
Merriam-Webster's Medical Dictionary, © 2007 Merriam-Webster, Inc.
mortality mor·tal·i·ty (môr-tāl'ĭ-tē)
1. The quality or condition of being mortal.
2. Death rate.
The American Heritage® Stedman's Medical Dictionary
in demographic usage, the frequency of death in a population
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.