A false seki is a position that looks like a seki but is not, because one player's stones are actually dead. A false seki may be a temporary seki that has collapsed, or it may be a position that arose in killing the dead stones.
This example comes from this Chinese site. After , - form a false seki.
Yes, a dead bent four in the corner is a false seki.
( on the 1-1 point lives.)
Bass: To me these three final diagrams do not seem like examples of false seki. They are plainly dead (we'll talk about the bent four later ;-) ) and I do not think there is any need for a term that means "dead, but somebody once misread it as seki". However, the first diagram displays a "proper" false seki, where there are groups that are locally in a seki, which will however collapse because some of the surrounding stones will get killed. In my opinion, this is a much more useful meaning for the term.
Googleplex?:I agree - in the last two examples it is possible for the target colour to make life.
W would play circle instead of 2 in the last example and in the previous one, black is able to make two columns of two, each as good as an eye.
MrTenuki: I think the reason that the last example is listed here is that the situation is similar to "real" sekis in one way: if either Black or White plays a stone locally, the other player may capture. What makes the seki false in this case, then, is the fact that, for White, capturing after Black plays a stone locally still does NOT make life (while Black may save the four stones if White plays locally first).
Zar?: We mention that a group is dead with a false eye, don't we? I could argue that the group is simply dead and that is simply not an eye. Consider it an educational term. The first example's just dead as well in my opinion.