In probability theory and statistics, kurtosis (from the Greek
word κυρτός, kyrtos or kurtos, meaning bulging) is a measure of the
"peakedness" of the probability distribution of a real-valued
random variable. Higher kurtosis means more of the variance is due
to infrequent extreme deviations, as opposed to frequent modestly
sized deviations.
Sometimes kurtosis gets confused with skewness, so I have added
links to both these terms.