ˈheptal,a. [irreg.f.Gr. ἑπτά seven + -al1.] = hebdomadal. 1857Dunglison Med.Dict. 208 Cycle, Hebdomadal or Heptal. A period of seven days, or years, which according to some, either in its multiple or sub-multiple, governs an immense number of phenomena of animal life.