I say pork because it is the original BBQ. Traditionally, buffalo was jerked, or cooked fast directly on coals or stewed.
dictionary dot com has that definition because that is becoming an accepted usage thanks to Kraft foods. They are really the ones responsible for all the confusion. The Webster's definition has been the same for 300 years and describes exactly what BBQ is. Pork and venison were the two types of meat most frequently cooked this way.
Now, since the 1500s people have referred to pork as BBQ. It has only been in the last hundred years or so that the Texas style has been developed. And it has only been in the last 50 or so years that people began generically calling anything cooked near a fire as BBQ.
If it walks like a duck and talks like a duck, it must be a duck.
If it walks like a pig and talks like a pig, it must be BBQ.
If it walks like a steer, and talks like a steer, it must be smoked brisket, steaks, veal, etc.
Hot Rod Hog Cookers Association, Charter Member, President