Log vs Lock is quite confusing to the casual user. Many foreign languages will not even have different SOUNDS for the two.
Whilst the concept of log-out is universally known, especially online, I propose changing the name of the LOCK feature to something that sounds different so as to be more easily differentiated mentally. For that matter, even to BUNNY OUT would work, but I’m sure we can come up with alternatives that both retain the explanation value AND make differentiation easier.
Like, “I was BUMPED OUT of my account even though I did not log out”. Or maybe “to BLIMP out” (a blimp being a secondary case for a movie camera, suppressing its noise to the outside, but not its function…). Or how about “SEAL OUT” - everybody loves seals and sea lions, right?
First of all, nowhere in the UI or documentation is the term “LOCK-OUT” used (looks like @DenBesten beat me to the punch on that observation).
Second, if you want more slightly more precise (and non-homophonic) terminology, I suppose that one could propose “Encrypt” and “Decrypt” as substitutes for “Lock” and “Unlock”, respectively.
… and would agree insofar, that it may be helpful (for new users) – maybe as a part of the new onboarding instructions – to have some more guidance here (for those technical terms).
In that case, the two phrases are very easy to differentiate, by the number of words/syllables. Even in the hypothetical scenario in which “Lock” is literally called “Log”, OP has conceded that “the concept of log-out is universally known”, and since the single-word phrase “log” by itself must mean something different, a user should be able to conclude that “log” ≠ “log out” (and therefore must refer to locking of the vault).
Computers make a distinction between locking one’s screen and logging out of one’s account. Is that not equally confusing? Personally, I think it helpful that Bitwarden mirror the operating-system terminology for actions that mostly mirror the behavior.