noun: (statistics) Any of the quantiles which divide an ordered sample population into five equally numerous subsets.
noun: (by extension) A subset thus obtained.
noun: (astrology) An aspect of planets that are distant from each other by one fifth of a zodiac (72°)
noun: (historical, obsolete) Alternative form of Quintilis: the former Roman name of the month July. [(historical) The month of the ancient Roman calendar which became July, the fifth month when the year began with March and the seventh after it began with January.]