Definition of 'Quartile'
A statistical term describing a division of observations into four defined intervals based upon the values of the data and how they compare to the entire set of observations.
Investopedia explains 'Quartile'
Each quartile contains 25% of the total observations. Generally, the data is ordered from smallest to largest with those observations falling below 25% of all the data analyzed allocated within the 1st quartile, observations falling between 25.1% and 50% and allocated in the 2nd quartile, then the observations falling between 51% and 75% allocated in the 3rd quartile, and finally the remaining observations allocated in the 4th quartile.
Try not to confuse a quarter with a quartile.