A lot of words are overloaded, across domains as well as within domains, that is not ideal but also no unsurmountable problem, you can always clarify your usage by providing definitions. There is certainly not much of a point to explain things in precise and correct terminology if this prevents the intended audience from understanding you. On the other hand, people aware of the technical details will have no big difficulties to understand something despite simplifications or inaccurate terminology.

I am actually not even sure whether zero-knowledge is not technically correct here. Terms like zero-knowledge proof or zero-knowledge protocol have very specific meanings and certainly do not apply here, but is zero-knowledge on its own really used for something more specific or other than not leaking knowledge? I also immediately thought of zero-knowledge proofs and protocols but nothing like that is mentioned anywhere, at least as far as I can tell, so it was kind if my mistake to read something into it that was not actually there.

EDIT: Zero-knowledge seems to indeed have a very specific technical meaning on its own [1], at least in the context of zero-knowledge proofs.

[1] https://en.wikipedia.org/wiki/Zero-knowledge_proof#Definitio...

This particular term is not overloaded. People familiar with encryption know it to mean something specific.

Thanks for the feedback. For what it's worth, we did try a bunch of alternative wordings, and Zero Knowledge was the phrase that non technologists found most accessible.

We prioritized making the explanation clear to non-experts vs. to the community of cryptographers.

I believe your explanation but it still strikes me as the wrong thing to do.

I'd like to propose "Zero Access", as in zero access to the plaintext.

That's actually not bad. I was fine with SpiderOak going for a term that is simple, catchy, and easy to market. Zero Access is the kind of alternative that might work. That specific one might have a problem: send perception of user having zero access to their own data when most clouds constantly reinforce "access from anywhere any time."

You're thinking along the right lines. I think variations of the words safe and vault have worked for other companies, too, given people understand what they do. "Your data is in a locked vault that we hold for you while you keep the keys or combination." That sort of thing.

They could go with "Know nothing".

(Or "Jon Snow", for short, if they can get away with it without being sued - "Jon S. crypto, we dont know nuthing" ;-)

This doesn't feel like the correct solution.

This happens all the time with marketing, surely this is not the first time you have seen a company co opt a term for marketing purposes.

This seems like a case of perfect being the enemy of good.