When you have electric motors that produce torque at any RPM, then as long as you can manufacture a motor to spin fast enough, you don't need gears.
The Model S is direct drive... so no gears.
So we'll just ignore that one gear in the box and the several that make up the open differential?
You could have a direct drive motor at each wheel. I'm not sure if the Tesla does this but it's one possibility.
There's one gear. So, yes, no gears.
I would classify one as more than none.
When I was 7 I got my first "bmx bike". It was awesome. When I turned 12 I got a "mountain bike" with 18!! Gears. I went from a bike with no gears to one with 18.
I think general usage of the term means that it fits Tesla -- even I f it's not technically correct