That's funny. A little digging into reference from the wiki you linked and then more digging turned up that because it's been so confused for so long that the meaning is being updated to reflect the ambiguity. After all, words mean what we all agree they mean. Crazy. So if we are all wrong consistently enough long enough we'll be correct!
I'd stick with the tradition meaning of semi and bi though. For the simple reason that while "bi" has been abused such that it has become ambiguous, "semi" hasn't. If you say semi-weekly the meaning is definitely two times per week.