hebdomadal

[hɛb'dɑmədl]

hebdomadal (adj.): 1610s, from Latin hebdomadalis, from hebdomas, from Greek hebdomas "the number seven; a period of seven (days)," from hepta "seven" (from PIE *septm; see seven) + -mos, suffix used to form ordinal numbers, cognate with Latin -mus. In later use as pedantic humor.