I like SB's answer. The thing is that you're looking for a one word answer (plumber, electrician... etc), when even those descriptions are weak...
Electrician= residential? Lineman? Generation plant?
Plumber= house? municipal? Naval?

Even Doctor has issues (like, a REAL Dr. or do you just think about things? HA HA).
Go one step further and say MD (Medical Doctor) and then when they ask you to look at the rash on their back.... and you have to explain that you specialize in researching left/right hemispherical interopability post-operative bisection for seizure treatment.........blank stare..... yeah, sure, let me look at that rash..

We are very much specialist working in a generalist world.