(statistics) any of the 99 numbered points that divide an ordered set of scores into 100 parts each of which contains one-hundredth of the total
"In the standardized test results, scoring in the ninety-ninth percentile meant her performance exceeded that of 99 percent of all other students."
Any of the ninety-nine points that divide an ordered distribution into one hundred parts, each containing one per cent of the population.
"In a standardized test where scores are ranked from lowest to highest, a student scoring in the 95th percentile has performed better than 95 percent of all test-takers."
In plain English: A percentile is a score that shows how many people performed worse than you on a test compared to everyone else who took it.
"She was happy to see that her test score placed her in the ninety-fifth percentile, meaning she scored higher than most students."
Usage: Use percentile to describe where a specific value stands relative to others in a group, such as saying a student scored better than 85 percent of their peers. Do not confuse it with percentage when calculating simple proportions or shares within that same distribution.
Francis Galton coined the word percentile in 1885 by combining percent with the suffix -ile. It was created to describe a specific statistical position within a distribution rather than simply indicating a percentage.