Looking for a really fancy way to say "balance" or "equilibrium"? Then stand up straight and try equipoise on for size.
When broken down into its etymological parts, equipoise is simply equi, meaning "equal," plus "poise." Equal poise: a balance of weight, forces or interests. So tight-rope walkers have excellent equipoise, as do balance beam gymnasts. And when the U.S. Senate is made up of half Republicans, half Democrats? There should be some equipoise of power, but that usually just leads to stalemate.