a graph showing the distribution of a population by sex, age, etc.
Origin of population pyramid
First recorded in 1945–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a pyramid-shaped diagram illustrating the age distribution of a population: the youngest are represented by a rectangle at the base, the oldest by one at the apex
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012