A biweek and a semiweek are not real or serious units of time
(please see footnote)
...therefore biweekly ought to mean twice a week, and semiweekly ought to mean once every other week. And same with the quarterly and yearly variants, etc.
This is how the math works on a rate. Weekly = 1 event/week. Biweekly = 2×1 event/week= twice a week. Semiweekly = 1/2×1 event/week = 1/2 event/week = (1 event every 2 weeks).
Nowhere are either a bi\[time period\] or a semi\[time period\] used in serious discourse, other than when discussing these botched rates. So these are clearly rates and not durations.
Can I get some \*combination\* STEM and linguistics folks to chime in here?
(this post is pending on r/unpopularopinion. I am new to this sub, and ready to have the it deleted if it violates any rules here)