Definitions for kurtosiskɜrˈtoʊ sɪs
Random House Webster's College Dictionary
a measure of a curve describing the statistical frequency distribution in the region about its mode.
Origin of kurtosis:
1900–05; < Gk kýrtōsis convexity
A measure of "peakedness" of a probability distribution, defined as the fourth cumulant divided by the square of the variance of the probability distribution.
Origin: From κύρτωσις, from κυρτός.