Medeski Martin & Wood are not sticklers about labels. For more than 20 years, keyboard player John Medeski, bassist Chris Wood, and drummer Billy Martin have coursed through the jazz world and jam-band environs with a funky, smart, and gritty sound all their own.

So when Wood ditched his upright bass for a plugged-in four-string on a few numbers during MMW’s “acoustic” show Friday at Jordan Hall, nobody was — or should have been — surprised; it’s best to simply trust in MMW.