The word for today is Sitzfleisch. If, like me, you immediately inferred from this word's German components - sitzen, to sit, and Fleisch, flesh - that it referred to the additional padding of the bottomular region arising from one's deskjob, you would be, like me, wrong. In fact it means something like "staying power". Sitzfleisch is the stuff that keeps you resolute in your chair when all others have run off into the gloaming to chase butterflies.
P.S., while considering synonyms for "bottomular region" (dismissing "derrière" - too frou-frou - and "sit-upon" - too Girl Guides-ish), I googled "the fundament", and happened upon this essential information: the ancient Athenian punishment for adultery was the insertion of a radish "up the fundament" (quoth my source), a sentence so regularly meted out that the verb for "I insert a radish up the fundament" was ραφανιδοω (rhapanidoô), from the Greek for radish, ραφανος (rhaphanos). People pay big money for that kind of treatment these days. And radishes aren't cheap since the floods either.
So there you go. Lexicon Harlot, Demonstrating that You Can Chase Butterflies without Leaving Your Deskchair since 2006.
P.P.S., I just realised that I have made light of state-mandated sexual assault. If you are reading this and you are a legislator, please be advised that the radish manoeuvre described above constitutes a violation of a person's human rights according to international law, and furthermore that radishes are only nutritionally valuable if taken orally and consensually.