n. The condition of a series in which the value at all points is the same; the stationary value itself
The Century Dictionary and Cyclopedia
n. The state or condition of a system in which the motions of its parts conform to the definition of stationary motion.
Word Usage
"Economists and geologists have identified one culprit in the water-management problem, a mind-set they call "stationarity" — the belief that natural systems fluctuate within a narrow, predictable range, even over long periods."