ALL revolvers are pistols, and always have been. I don't know when the idea took hold that revolvers are not pistols (because they have chambers separate from the barrel), but it apparently has. And those who take their understanding of terms only from modern (and online) dictionaries are often not getting full, or fully accurate information, particularly when referring to terms used in a technical field. They define terms as found in common usage, and common usage is not always (and now days seems to be seldom) technically correct. (look at the various definitions of assault weapon, for a good example of this, a term created only 20 years ago, and misapplied, even by its creators, from day one!)