Expedientially is the adverb form of expediential, which is a form of expedient. These words all ultimately derive from the Latin word expedīre, which means “to disengage” or to “set the feet free.” It is based on the root ped–, meaning “foot” (as seen in words like pedal and pedestrian). A closely related word is expedite, which means “to speed something up.”

The word expedient is often used in the phrase politically expedient, as in We can’t always please all our constituents—we have to do what’s politically expedient to accomplish our larger goals. If an action is called expedient, it can be interpreted as meaning that it’s the advisable thing to do, or the advantageous thing to do. After all, isn’t it advisable to the advantageous thing? We’ll let the politicians sort that one out, as long as they do it expedientially.

Regardless of what it truly means, expedientially is rarely used. Some people may mistakenly use it when they mean exponentially, which most commonly means “increasing steadily and usually rapidly.” (We don’t expect use of expedientially to increase exponentially anytime soon, but you never know. It may become the expedient thing to do.)

Did you mean expediential?