This is one of those ones that's a tragedy. Biweekly "should" always mean every two weeks. Twice a week is "semi-weekly", aka every half a week.

But regardless of what it "should" mean, people use it wrong often enough that you have to check every time, not because the word is ambiguous, but because people are often mistaken.

It's a shame, but it's part of human communication 😅

There's also semi monthly, which is two times a month, as opposed to every two weeks, which is what biweekly is

Check the podcast episode “A Problem Squared - 121 = Bi-annuals and Diagonals”. In it, Matt and Beck discuss what these terms even mean, and propose a solution.

Fortnightly already exists as a term though, why would biweekly mean the same thing?

The rule makes perfect sense (and is how I’ve always used it), but this article actually misses a major point which I just learned last week when talking to some native Spanish speakers. In most English speaking countries, the week starts on Sunday. This isn’t the case for many, many other countries though. So saying “this Friday” on a Sunday really really confuses people. That’s exactly what happened to me last week because it was a Sunday and we were talking about a Friday and she got very very confused.

I find Thursday (for this week) and Thursday next (for next week) adequate and am seldom called on for clarification, seems to follow the pattern of the rule (thanks for that) but is more economical.

Another problem is that system requires agreeing on what a week is, and there's disagreement over whether Sunday starts or ends the week.

In Norwegian we operate with "førstkommende" which translates more or less directly to "first-coming". It's extremely practical when planning dates, because you can always just say "Not the first-coming Thursday, but next Thursday", or "On the first-coming Thursday", and it's completely unambiguous that you mean the first Thursday we encounter from the moment of speaking.

This Thursday is already in the future. It has no meaning of you say it on a Friday. Then it’s ”this Thursday coming“ or just “Thursday coming”

At least here in the UK that’s the only way I’ve ever heard it used

“This Thursday” is for the Thursday contained within the Sunday–Saturday interval you’re currently in.

Except according to ISO 8601, Monday is the first day of the week, and it is the definition used in some english-speaking countries (Ireland, occasionally the UK). That means every Sunday there is a definite ambiguity as to which day is "this Thursday".

"This Thursday" is the closest Thursday coming up, "next Thursday" is the next one after that. The exception is if you're already passed "Thursday" that week, then it's "next Thursday" until the new week starts.

I’m with you so far as “next” should always the next occurrence of the day, and maybe in some places it does. But practically it doesn’t work. In every place I’ve lived it works like this: “this week” isn’t a set Monday – Sunday like you suggest, but a rolling seven days. Its Monday as I write this, “this Wednesday” is two days from now, while “next Wednesday” is the following. Same for this vs next weekend. If it’s Friday, “this Monday” is three days away. Rolling seven days.

“This” cannot be used for the day of week you are currently on, nor can it be used for previous days.

I feel strongly that "next" Thursday should be not the next instance of a Thursday but rather the first instance of a Thursday past the contained set of the current week (so the next row on a calendar). I.e. if it's Tuesday, "next Thursday" isn't the Thursday two days from now but the Thursday 9 days from now.

Yes, youre right

No, you're wrong. This weekend means the next up coming weekend. Next weekend means the one after that. Unless you were talking super early on Sunday morning and you were confused whether he meant that afternoon. But like, critical thinking skills are important in communication.