[kwon-tahyl, -til]
noun Statistics.
  1. one of the class of values of a variate that divides the total frequency of a sample or population into a given number of equal proportions.

Origin of quantile

1935–40; quant(ity) + -ile noun suffix, on the model of percentile
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018