Well, although it probably was mostly a marketing word, technically it is correct.
I think they may wanted to make it look different from the game system like the Oddesey that was just a bunch of analogue circuits.
Although this is now recognized as the first video game system, I still don't agree. It doesn't have any logic at all. It's just some dots and stripes on the screen produced by analogue stuff. That's not a video game IMHO, but then again who decides about the definition of a video game ?