Septuagesima :: Septuagesima (n.) The third Sunday before Lent; -- so called because it is about seventy days before Easter.
Septuagesimal :: Septuagesimal (a.) Consisting of seventy days, years, etc.; reckoned by seventies..
Septuagint :: Septuagint (n.) A Greek version of the Old Testament; -- so called because it was believed to be the work of seventy (or rather of seventy-two) translators.
Septuary :: Septuary (n.) Something composed of seven; a week.