Most of the time, “meantime” is the word you want. It is one word and means “the time between two events.” “Mean time” is two words and is used in a few set phrases, such as Greenwich Mean Time. The two are not interchangeable.
Quick answer
- Meantime (one word) means the period between two points in time. Example: The food will be ready in ten minutes. In the meantime, set the table.
- Mean time (two words) uses “mean” to mean “average” or “middle.” Example: Greenwich Mean Time is the time at the Prime Meridian in London.
If you are talking about waiting, or something happening while you wait, use meantime.
What “meantime” means
“Meantime” is a noun and an adverb. It is about the gap between now and a later event, or between two events.
As a noun, it almost always appears in the phrase “in the meantime.”
- The doctor is running late. In the meantime, please fill out this form.
- Your new laptop arrives on Friday. In the meantime, you can use mine.
As an adverb, it can stand alone, usually at the start of a sentence with a comma after it.
- Mix the dough and let it rest. Meantime, heat the oven.
This adverb use is more common in British English. In American English, “meanwhile” is the more usual choice. The meaning is the same.
You will also see “for the meantime.” It means “for now,” but many writers prefer “in the meantime” or “for now.” Both are understood.
What “mean time” means
When written as two words, “mean” is a separate word that describes “time.” In these cases, “mean” means “average” or “middle.” You will see it in a small number of set phrases.
- Greenwich Mean Time (GMT): the time at the Prime Meridian, which runs through Greenwich, London. It is based on the average position of the sun.
- Mean solar time: time measured by the average length of a solar day, not the exact position of the sun on a given day.
- Mean time between failures (MTBF): the average time a machine or system works before it breaks down.
- Mean time to repair (MTTR): the average time it takes to fix something after it breaks.
In all of these, you could swap “mean” for “average” and the sentence would still make sense. That is a good sign you need two words.
“Mean” can also mean “unkind,” as in “a mean time.” That is rare and not a standard phrase. If you mean “a bad time,” “a hard time” is the usual wording.
Side-by-side comparison
| Meantime | Mean time | |
| Words | One | Two |
| Meaning | The time between events | Average time |
| Common phrase | In the meantime | Greenwich Mean Time |
| Used in | Everyday writing | Science, engineering, time zones |
A simple test
Replace the word with “in the meantime” → “meanwhile” or “until then.” If the sentence still works, write meantime as one word.
Now try replacing “mean” with “average.” If the sentence still works, write mean time as two words.
Here are some examples:
- The plumber comes tomorrow. In the ___ time, don’t use the sink. → “Until then” fits, so write meantime.
- The ___ time between failures is 400 hours. → “Average” fits, so write mean time.
- London uses Greenwich ___ Time in winter. → “Average” fits, so write Mean Time, with capital letters because it is part of a name.
Common mistakes
“In the mean time” (two words) for waiting. Writers split the word because “mean” and “time” are both familiar words. Most dictionaries list the one-word form. Write: In the meantime, I’ll keep working.
“Meantime” in a technical phrase. Writing “meantime between failures” is wrong. The phrase means an average, so it needs two words: The mean time between failures is 400 hours.
Quick questions
Is “in the mean time” ever correct?
You may see it in older books or informal writing. Today, most dictionaries and style guides prefer “in the meantime.” Use the one-word form.
Is “meantime” the same as “meanwhile”?
The meanings are very close. “Meanwhile” is more common in American English, and it can also mean “at the same time,” as in Dad cooked. Meanwhile, the kids played outside. “Meantime” focuses more on a waiting period.
Do I capitalize “mean time”?
Only when it is part of a name, such as Greenwich Mean Time. In “mean time between failures,” it stays lowercase.
Takeaway
Use meantime (one word) for the time between events: “in the meantime.” Use mean time (two words) when “mean” means “average,” as in Greenwich Mean Time or mean time between failures.
Read more about these:
- I Am Confused vs I Am Confusing: Which One Is Correct?
- I Fall Asleep vs I Fell Asleep: Which One Is Correct?
- Timewise vs Time Wise: Which Spelling Is Correct?
- Resend vs Re-send: Which One Should You Use?
I write clear, practical English lessons for everyday use. On Lingotexting, I break down grammar, vocabulary, and word types into simple ideas you can apply quickly. My focus is accuracy, real examples, and helpful visuals, so learners build confidence, improve writing, and communicate naturally in school, work, and daily life.