When an event is rapid, it happens “quickly.” When it’s highly audible, it’s “noisy.” It can occur “publicly” or “privately.” If it’s an action taken by a person, it can be done “firmly,” “tentatively,” “happily,” “sadly,” and so forth. But what if the event determines something for sure — the price of your last tank of gas is what finally makes up your mind to switch to an electric car, for example?
English comes to the rescue again, because there’s a word for an event like that: “decisory.” It’s been around for quite a while, but lurking in the shadows. Samuel Johnson’s 1755 dictionary defined it: “Decisory..Able to determine or decide.” By that time, “decisory” had already been part of the language for at least a century.
“Decisory” was adapted from the Latin word “decisorius,” which is also the source of “decide.” Some of the early uses, in the 1600s in particular, had to do with a “decisory lot,” which is the single vote that settles an issue. By the 1800s it was more likely to stand alone, as in “She had begun her work without any decisory plan” (1895). And by the 1900s “decisory” had become pretty firmly entrenched in the kind of bureaucratic language that never uses 2 words where 10 will do: “In all matters pertaining to student (and faculty) living arrangements, the university community as a whole has the right to exercise collective decisory authority.” That last bit is from 1969. With that kind of attitude, it’s no wonder there was unrest on college campuses in the ‘60s.
“Decisory” isn’t a word most English speakers are familiar with, and statements like that one from 1969 are probably the reason. Here’s another, from 2005: “The very fact that the request [for a bus route] takes place shows that the decisory power of the higher instance [sc. the city hall] is not put into question at all.”
Writing like that isn’t intended to communicate so much as to dictate. It’s the kind of thing you find in the fine print on page 249 of the terms you supposedly agree to by doing something completely unrelated to agreeing to anything at all, like scrolling a web page or walking through a door. Nobody reads that stuff, and as a result, “decisory” is usually a wasted word that really isn’t decisory at all.
