"of or pertaining to the science or study of wealth or riches," 1853, from Greek ploutos "wealth" (see Pluto) + ending from economic. Fell from currency 1870s, revived 1990s. Related: Plutonomy (1851); plutonomics (1991, a 19c. word for "the science of wealth and the natural laws governing its production and distribution" was plutology); plutonomist (1869).
1891, "release of air," noun of action from deflate (q.v.). In reference to currency or economic situations, from 1916. Related: Deflationary.