English is messy. Really messy. If you've ever sat in a boardroom feeling like an idiot because you weren't sure if the "bimonthly" meeting was happening in two weeks or two months, join the club. It's a linguistic disaster.
So, what is bi monthly mean in the real world? Honestly, it means two completely different things at the same time. It is a word that functions as its own antonym. Merriam-Webster, the Oxford English Dictionary, and basically every style guide on the planet will tell you that bimonthly can mean "twice a month" or "every two months."
It’s a coin flip.
This isn't just a quirk of grammar; it’s a genuine problem for payroll departments, magazine publishers, and project managers. If a freelance contract says you’ll be paid bimonthly, you might be expecting a check every 15 days, while your client thinks they don’t have to cut a check for eight weeks. That is a massive gap.
The Great Definition Divide
Let’s look at the prefix "bi-." In most cases, it means two. A bicycle has two wheels. Bigamy involves two spouses. Simple, right? But when we apply it to time, the logic breaks.
The primary definition, at least according to most linguistic purists, is "occurring every two months." This aligns with "biennial," which means every two years. If you subscribe to a bimonthly journal, you usually get six issues a year.
But then there’s the second definition: "occurring twice a month." This is where the chaos starts. People often use "bimonthly" interchangeably with "semimonthly."
Why do we do this? It’s likely because of how we process the word "weekly." If "biweekly" can mean twice a week (though it usually means every two weeks), our brains naturally apply that same messy logic to the month.
Bimonthly vs. Semimonthly: The Paycheck Test
If you want to be precise—and you probably should if money is involved—you need to know the difference between bimonthly and semimonthly.
Semimonthly is far more specific. It means twice a month, usually on fixed dates like the 1st and the 15th. In a standard year, a semimonthly schedule results in 24 events.
Bimonthly, when used to mean every two months, results in only 6 events per year.
Imagine the frustration of a salaried employee who thinks they are on a semimonthly pay cycle but the boss thinks the agreement is bimonthly. One person expects 24 paychecks; the other is planning to send six. That's a lawsuit waiting to happen.
Bryan Garner, the authority behind Garner's Modern English Usage, suggests that the "every two months" definition is the "traditional" one, but he acknowledges that the word is so badly mangled in common usage that it’s almost useless. He calls these kinds of words "skunked terms." A skunked term is a word that is so disputed or misused that any use of it will distract or confuse the reader, regardless of which definition you intended.
Real World Examples of the Confusion
Look at the publishing industry. The Atlantic was famously a monthly magazine for years, but many smaller literary journals operate on a bimonthly basis. When they say bimonthly, they almost always mean every two months. You’ll see a January/February issue, then a March/April issue.
Now look at corporate meetings.
If a manager says, "We’re moving to bimonthly check-ins," half the team will clear their calendars for two weeks from now. The other half will assume they have eight weeks of peace.
It's a mess.
In the world of finance, interest can be compounded bimonthly. Here, it usually refers to every two months. If you’re looking at a loan document, you better check the fine print. Don't just assume. If the math doesn't add up to six or twenty-four periods, you're looking at a typo or a very creative banker.
Why Does This Confusion Even Exist?
It comes down to the "bi-" prefix being overworked. We use it to describe frequency (how often) and intervals (the gap between).
- Frequency: Twice in one period.
- Interval: Once every two periods.
The English language doesn't have a built-in "frequency" protector for the word month. We have "fortnightly" for every two weeks, which is a beautiful, specific word that Americans stubbornly refuse to use. Without a "fortnightly" equivalent for months, we just grab "bimonthly" and hope for the best.
How to Stop the Madness
If you are writing a contract, a calendar invite, or a newsletter, stop using the word bimonthly. Just stop.
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It doesn't matter if you're "right" according to a specific dictionary. If your audience doesn't know what you mean, you've failed as a communicator.
Instead, use these phrases:
- Every two months. (Clear, impossible to misinterpret).
- Twice a month. (Simple, direct).
- Semimonthly. (Technically accurate for twice a month, though some people still find it jargon-heavy).
- On the 1st and 15th. (The gold standard for clarity).
The Mathematical Perspective
Let's do the math.
If you do something bimonthly (every two months):
$12 \text{ months} / 2 = 6 \text{ times per year}$.
If you do something bimonthly (twice a month):
$12 \text{ months} \times 2 = 24 \text{ times per year}$.
The difference is a factor of four. In any technical field—engineering, accounting, pharmacology—a factor of four error is a catastrophe. If a patient is told to take a "bimonthly" dose of a heavy medication and they take it twice a month instead of every two months, that’s a potential overdose.
Expert Nuance: The Ambiguity of "Biweekly"
The problem isn't just with months. "Biweekly" is arguably worse.
Since there are roughly 52 weeks in a year, biweekly (every two weeks) means 26 occurrences. But if someone thinks it means twice a week, they’re expecting 104 occurrences.
The linguistic root of this confusion is hundreds of years old. Etymologists trace the "twice a" vs "every two" conflict back to the 19th century. Even then, people couldn't agree. If 150 years of education hasn't fixed the definition, a blog post won't either. We just have to work around it.
Insights for Business Owners
If you're running a business, clarity is profit.
When setting up recurring billing for a SaaS product or a subscription box, never label the tier as "Bimonthly." You will get customer support tickets. You will get chargebacks.
Label it "Every 2 Months" or "Every 60 Days."
The same applies to employee handbooks. If you describe your pay period as bimonthly, you’re asking for a headache during the onboarding process. Most payroll software (like Gusto or ADP) will ask you to choose between "Biweekly" (every two weeks) or "Semimonthly" (twice a month). Notice how they rarely use the word "bimonthly" in their setup menus? They know better.
Final Verdict on the Word
The answer to what is bi monthly mean is ultimately: whatever the speaker thinks it means.
It is a failed word. It’s a linguistic ghost.
If you encounter it, you must ask for clarification. Never assume. If you see it in a contract, strike it out and replace it with "every two months" or "twice a month."
Actionable Steps for Clear Communication
To avoid the "bimonthly" trap and ensure your scheduling is foolproof, follow these steps:
- Audit your existing documents: Check your contracts, website FAQs, and internal calendars for the word "bimonthly."
- Replace with "Every Two Months": If you are referring to an interval of 60 days, use this specific phrase.
- Use "Semimonthly" for Payroll: If you mean twice a month, use "semimonthly" but accompany it with specific dates (e.g., "the 15th and 30th").
- Define your terms: If you absolutely must use the word bimonthly for branding reasons (like a magazine title), include a small note in the masthead or footer that explicitly states "Published six times a year" or "Published 24 times a year."
- Ask for clarification immediately: If a client or boss uses the term, reply with: "Just to be sure we're on the same page, do you mean twice a month or every other month?"
By being the person who asks the "dumb" question, you save yourself and your team from weeks of misaligned expectations. In business, being right is less important than being understood. Stop using "bimonthly" and start using plain English. It's the only way to keep your calendar from falling apart.