man-year (m?n?yîr?)n. A unit measuring the work of one person in a year, based on a standard number of man-days.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.man?-year` n. a unit of measurement based on a standard number of man-days in a year of work. [1925?30] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.