I usually say “semiweekly” to mean twice per week. I also say “semimonthly” to mean twice per month (24 times per year) as opposed to “biweekly” (26 times per year).

This is the only word I know of whose meaning can be redefined by majority consensus.

Case in point, my workplace wanted a bi-weekly committee meeting for our team to work on stuff over a zoom call. I asked what days these meetings would be held and they all agreed "Just Thursdays". When I tried to argue that a bi-weekly meeting necessarily means that there must be two distinct dates per week, they all agreed that bi-weekly obviously means every other Thursday and that I didn't understand what the word bi-weekly meant 😒

The fact that American English doesn't have the word 'fortnightly' is incredibly confusing on every level.

Biweekly is every two weeks (fortnightly)

Semi-weekly is twice a week.

Same rule as bimonthly and semimonthly.