OK, I'll give on this one, it ain't worth the trouble and besides, we're all right to a degree.
Prior to the invention of repeating handguns, all firearms designed to be used with one hand were properly referred to as pistols. For a variety, you had "matchlock" pistols, flintlock pistols, and percussion pistols, all designed to be easily carried and capable of being fired with one hand. Sam Colt's invention (if you don?t count the Collier), gave us a "repeating pistol", more correctly called a "revolving pistol", usually called a revolver for short.
The invention of the "self-loading pistol" further complicated the distinction, but everything still followed as you would expect. We now had pistols designed to be fired with one hand that commonly became known as "automatics", but this of course, was simply a contraction of "semi-automatic pistol". We even have a couple of full automatic pistols if you count some foreign variations of the 1911 design, the Glock 18, and the Model 712 Broom-handle Mauser.
How about a semi-automatic revolving pistol? Yep, there is/was such a thing, built by Webley Fosbury in England (in several models, actually). The top end of pistol containing the cylinder was designed to move to the rear on "rails" like the slide on a .45. The recoil produced by firing the cartridge, caused the top end to travel to the rear cocking the hammer. A stationary vertical pin in the lower frame tracked in a "zigzag" channel in the cylinder causing it to turn to the next chamber as the top end moved rearward. The first time I read "The Secret Life of Walter Mitty" I thought the author had really blown his stack, alas, 'twas I that was wrong, the lad had described an existing pistol.
Much of the confusion of the terminology came about years ago, when the Army put out their manual on "Pistols and Revolvers". They were of course, incorrect in their nomenclature, the manual should have been named simply "Pistols".
Let's sum this thing up before it gets out of hand like the "Gnu" jokes. First of all, any handgun can be described with the word "pistol", but all can be "sub-categorized" as follows:
Pistol = Any firearm designed to be fired with one hand (yeah, I know, everyone uses two hands these days, but here we're talking definitions).
Sub categories:
Single Shot Pistols (Black Powder or Cartridge)
Revolving Pistols (black powder or cartridge)
Semi-Automatic Pistols (gas, recoil and blowback)
Semi-Automatic Revolving Pistols (Webley Fosbury)
(Full) Automatic Pistols (usually rare variations of existing semi-automatic pistols)
If you really want to spice up the conversation, you can even talk about what makes a revolving pistol work, as in "single action revolving pistols", "double action revolving pistols", "double action only revolving pistols", etc., but here we're getting more properly into nomenclature instead of definition.
At any rate, the next time someone starts talking about pistols and revolvers, you can smile and know that they are using two words to describe the same object. Just keep in mind that all revolvers are pistols, but not all pistols are revolvers (and if one smart cookie mentions that I am technically wrong and cites the example of the Colt's Revolving Rifle, I'd have to admit that he has just mentioned the exception that proves the rule!).
I'll forgive you if you wanna' call your ol' Granpappy's single action a "thumbuster", "cutter", "smoke pole", "plow handle", or "hawg leg", but never forget Clint Eastwood's quote in "The Outlaw Josey Wales", Ol' Josey says "well, ya gonna' pull them pistols, or whistle Dixie?"
Now, Josey knew his nomenclature! C&B