Why does bi-weekly mean "every two weeks?" This has always bothered me because intuitively it should mean "twice a week."

It means both, twice a week and every two weeks. It's confusing but what part of english isnt?

I'm wondering the same thing about Bible. Does it mean twice per Ble or every other Ble?

I was taught that the "bi" prefix was a multiplier and "semi" was a divider.

That meant biweekly, bimonthly, biannually were every 2 weeks, months, years and semi-weekly, semi-monthly, semi-annually were every half a week, half a month, and half a year.

Then the real world intruded and I've been confused ever since. About the only time I hear "semi" and "bi" used on a regular basis the way I expect is with pay periods. Biweekly is every two weeks and semi-monthly is twice a month.

Canada, by the way.

PS: I suppose bisexual and semi trailers also fit my expectations.

It means both. Welcome to English.

Bi-weekly means twice a week and every two weeks. Look it up in the dictionary of you choosing.

It's because of British English, and the fact that American English seems to have dropped a word which is caused confusion.

Bi-weekly means two times a week.

Fortnightly means every 2 weeks. But American English seems to have lost the word fortnightly, so there is this ambiguity now.

this is TIL, for me. "fortnightly" almost always solves it.

I always think the rule was "bi-" for "two" like bicycles VS semicycles.

dictionary people say it is up to the sayer to avoid confusion.

The real answer is to solve this by using different terms. For instance, "twice per week" or "every other week".

Don't try to get anyone to agree on a definition, it's just begging for problems.

Bi means 2. Bi weekly means 2 weeks.

Semi means half. Semi weekly means every half week or twice per week.

I prefer to use "semiweekly" for twice in a week, and so on for other periods.

Wait, so bi-weekly and bi-monthly mean almost the same thing (every 14/15 days)? That's insanity!

There was often much confusion about this in the past because as you said it can mean multiple things. We seem to have gone away from any proper etymological use of the word 'bi' and have defined (for the most part) biweekly to be every two weeks, bimonthly to be twice a month, biannually to be twice a year (that one maybe not). Legal documents that I see don't use those terms to avoid confusion.

The banks use “biweekly” and “semiweekly” to avoid this exact kind of ambiguity. Biweekly would be twice a week, while semiweekly would be every other week.

It comes up in banking a lot because of payroll. If you get paid every other week, you get paid semiweekly. But if you get paid on the 1st and 15th of every month, you get paid bimonthly.

I think the conflict is between invisibly different sub-word groupings. I think of them as "(biweek)ly" = "happens every biweek" = "happens every two weeks, vs. "Bi(weekly)" = "happens twice as much as weekly" = "happens two times every week".

That doesn't really help the ambiguity, so I prefer other ways of describing the recurrent timing of events when there isn't anything obviously disambiguating them - for example, if I create a digital calendar event and name it "biweekly event", the existence/nonexistence of repeated calendar events makes it obvious what is meant.

Compare semi-weekly.

In Australia it means twice a week, we say fortnightly (fourteen-nights) for 2 weeks.

An old word that fell out of use to describe a two-week period is "fortnight."

It should make a come back, but I fear the current generations would always misspell it for... reasons.

Fortnightly means every two weeks. Bi weekly means twice a week.

As a non-native English speaker, this is what I thought when I was first introduced to this word. I was even fighting it when I was told it meant "every two weeks". Then I caved and went with the flow. You are the first person to ever agree with me. I'm not crazy. Thank you.

The word for "biweekly" you are looking for is "semi-weekly".

Because "weekly" is kind of a fraction (1/week), and 2/week and 1/(2week) are very different, but both can be pronounced very similarly. Read kind of like (2-week)ly and 2-(weekly). Which is why both meanings are used, so you need to use context to disambiguate, or just guess if context isn't available.

This is also the reason why in this thread people say "semiweekly" is the other option, but they don't all use the same other option. You have the same, but inverse problem there.

Think of biweekly and biweekly as homonyms, they can mean either and you figure out the meaning through context.

Very few things happen twice a week, biweekly usually means every second week, but it's never used because fortnightly is preferred.

Others here are saying bimonthly means twice a month but I've never heard it used that way. Again, very few things happen twice a month, it's always fortnightly which is not the same. Lots of things happen every second month, "the board meets bimonthly", that means 6 times a year.

Biannual always means twice a year because what things do you do every second year?

In all cases you can use the alternative meaning like "I visit my cousin biannually" and it's not incorrect but of course "I visit my cousin every second year" avoids confusion.

we have bi like in binary(yes, no/ one week yes other no) and bi in like bisexual(atraction to 2 genders/ twice a week) i think the problem is more deep than the week

Yes it does not make sense English is a dumb language. See also: bicycle and bisection

Bicebtennial

So if "bi" is twice, does that mean if you are 'bi-sexual', you only have sex twice?

weekly is once a week. bi-weekly is weekly times 2

This is semantically correct and everyone else is wrong. Semi weekly is every other week. The widespread confusion on this is the surest sign that degeneracy prevails in the world.