As 140 other pistol-related images have the "revolver" tag, I decided to start a "semiautomatic" tag which separates these pistols from the revolver type.
I would think "pistol" in the modern context already generally denotes semi-autos while including more rare types such a full-auto pistols and single-shot weapons. "Revolver" implies a revolving cylinder but would also include oddities such as the Mateba automatic revolver (Togusa's gun in GitS/KK), Colt and Patterson revolving rifles and various fantasy weapons. Where pneumo-electric plastic pellet launchers such as these would fall in within this system (other than "airsoft", as tagged) seems open to question.
It depends on where you are from. If you visit http://en.wikipedia.org/wiki/Pistol#Multiple_senses_of_the_word_.22pistol.22 you will see that American usage does seem to link 'pistol' with 'semiauto' whereas Commonwealth usage equates 'pistol' with several types of handgun including both semiauto and revolver, as well as machine pistol and derringer.
Now, can anybody say for sure whether that's a slide-mounted safety on the semiauto pistol? If so, it's probably not a Colt but more likely a Smith & Wesson 4500-series...