Most planes (all civilian planes?) will gradually approach a particular airspeed if flown straight with no elevator input. This airspeed is determined by the elevator trim.
Is there a common term for what that speed is?
The most obvious thing to call it is the "trim speed".
Though that's a bit of a misnomer, since even planes without trim (such as these $8 gliders I bought at Jo-Ann's) have a "trim speed".
@TannerSwett I used to deliver to an FBO. The normal procedure at the time was to drive right up to the front. Although it was technically a taxiway they used it like a parking lot.
I filled in on that route about a year ago and, unbeknownst to me, the FBO had changed ownership. The new people completely wigged out when I drove into the taxiway like I had in the past.