They tried to coin a new (unrelated) sense of this term about two years ago in order to try to explain services where the service provider doesn't have access to your data. I agree that it's confusing because of the much more clearly established technical term with a different meaning, and I don't think SpiderOak's sense has caught on outside of the company.

Can anyone suggest a better term? Some people like "end-to-end encrypted" even in this context, but that doesn't really make sense for data at rest, which is almost all of what SpiderOak's products deal with.

Edit: SpiderOak has had a super-hard time marketing their privacy features to people who aren't already familiar with the fairly stark distinctions in play in different access models. I'm sure they would appreciate if someone came up with a straightforward way to explain "products where the service provider doesn't have access to your data, and can't get access without your help in any circumstances because of technical constraints".