life expectancyn. The number of years that an individual is expected to live as determined by statistics.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.life expectancy n (Biology) the statistically determined average number of years of life remaining after a specified age for a given group of individuals. Also called: expectation of life Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014life? expect`ancy n. the number of years an individual is expected to live, according to statistical estimates taking into account sex, physical condition, occupation, etc. [1930?35] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.