"gear" is not marketing speak, but if you ask marketing, you'll get a marketing answer.
Actually "gear" is a term for "something we don't have a name for so we have to give it one because it's not anything we've come across for that has a name".
It refers to a unit of stuff bounded right now by a linux user account with some template files inside, some control glue outside and which might later be replace or augmented with either libvirt-lxc or other containment tools (like Docker or others).
I'm one of the guys who argued for "local user account" because I hate making up names for stuff like that when perfectly good descriptions will do, but people (developers) that was too long to write all the time so "gear" was coined so we'd know what we were talking about without rambling forever just to be precise and pedantic. Like that.
Yeah, the marketing guys got hold of it and if they try to define it for you you'll get some technobabble. That's because no one's really interested in what it really is except for dirt-under-the-fingernails implementers.