The Atari 2600 was originally the Atari VCS (it stood for Video Computer System). It was only later, when Atari released the ill-fated Atari 5200, that it started being called the 2600. Most people, though, just knew it as an Atari - all of which are infinitely preferable to the name Atari founders Nolan Bushnell and Ted Dabney originally chose for their company: "Syzygy".
The name Atari was, by all accounts, plucked from a mind-cloud, and apparently has no actual meaning (though it is close to a Japanese word meaning hit or strike).
Of course, the VCS wasn't Atari's first games machine: that was Pong, which "popularised" a type of video tennis game that Bushnell had seen running on the Magnavox Odyssey home console (for "popularised" read "ripped-off" - Bushnell settled a lawsuit from Magnavox out of court, later claiming, somewhat uncharitably, that "I absolutely did see the Odyssey game and I didn't think it was very clever").
Developed off the back of its Pong profits - a two-word phrase only ever previously used by Gallic entertainer McFlatulus The Fartslinger - the 2600 landed in the US in 1977, with the UK following a year later. Included in the box were two joysticks, two paddle controllers, and a copy of Combat - a multiplayer shoot 'em up, based on two separate Atari arcade games, in which players went at one another in tanks or planes.