any of the values in a series dividing the distribution of the individuals in the series into one hundred groups of equal frequency
any of these groups
adjective
of a percentile or division into percentiles
See percentile in American Heritage Dictionary 4
(pər-sĕnˈtīlˌ)
noun
One of a set of points on a scale arrived at by dividing a group into parts in order of magnitude. For example, a score equal to or greater than 97 percent of those attained on an examination is said to be in the 97th percentile.