Used and loved by millions
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.

Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com
one thing
Grammar usage guide and real-world examplesUSAGE SUMMARY
"one thing" is correct and usable in written English.
You can use it to refer to a single concept or idea. For example: "I know one thing for sure - I will always love you."
✓ Grammatically correct
News & Media
Wiki
Science
Alternative expressions(6)
Table of contents
Usage summary
Human-verified examples
Expert writing tips
Linguistic context
Ludwig's wrap-up
Alternative expressions
FAQs
Human-verified examples from authoritative sources
Exact Expressions
60 human-written examples
One thing–.
News & Media
One thing, and one thing only.
News & Media
One thing I know.
News & Media
ONE thing seems certain.
News & Media
One thing is certain.
News & Media
One thing is sure.
News & Media
One thing — that's all.
News & Media
One thing that's involved?
News & Media
One thing, he said.
News & Media
One thing the I.M.F.
News & Media
One thing seems likely.
News & Media
Expert writing Tips
Best practice
Use "one thing" to clearly introduce a single, specific point or consideration within a broader context. This helps to focus the reader's attention.
Common error
Avoid using "one thing" in very simple sentences where it might sound redundant. Instead, directly state the point without the introductory phrase. For example, instead of "One thing to remember is to bring your passport", simply say "Remember to bring your passport".
Source & Trust
88%
Authority and reliability
4.5/5
Expert rating
Real-world application tested
Linguistic Context
The phrase "one thing" functions primarily as an introductory phrase. It is used to single out and emphasize a specific aspect, point, or consideration within a broader context. Ludwig AI indicates that it follows standard grammar rules and is widely used. Examples show it frequently introducing a key piece of information or a crucial element.
Frequent in
News & Media
62%
Wiki
13%
Science
6%
Less common in
Formal & Business
4%
Reference
0%
Encyclopedias
0%
Ludwig's WRAP-UP
In summary, "one thing" is a grammatically sound and frequently used phrase that functions as an introductory element to emphasize a specific point or idea. Ludwig AI confirms its correctness and broad applicability. Its neutral register allows it to be used in various contexts, most commonly in News & Media. While versatile, overuse in simple sentences should be avoided to prevent redundancy. Alternative phrases such as "a single aspect" or "a particular point" can provide nuanced variations, but the core function remains consistent: to highlight a singular element for attention.
More alternative expressions(10)
Phrases that express similar concepts, ordered by semantic similarity:
just one item
Implies simplicity and limitation to a single element or object.
a particular point
Directs attention to a specific item or issue, similar to "one thing" but more precise.
one specific item
Adds clarity by specifying "item", which could imply a concrete object or piece of information.
only one detail
Highlights the restriction to a single, often small, piece of information.
a single aspect
Emphasizes a particular element or facet being considered, more focused than "one thing".
a unique element
Stresses the distinctiveness of the element, providing a slight variation in focus.
a solitary detail
Highlights the isolated nature of the detail, adding emphasis to its uniqueness.
a lone factor
Emphasizes that only one factor is being considered, providing a more analytical perspective.
a certain matter
Introduces a topic or concern that is being singled out for attention.
the main thing
Shifts the focus to the most important aspect, adding a sense of prioritization.
FAQs
How can I use "one thing" in a sentence?
You can use "one thing" to introduce a specific point or idea. For example, "One thing to remember is to always back up your data."
What are some alternatives to saying "one thing"?
Alternatives include phrases like "a single aspect", "a particular point", or "just one item", depending on the context.
Is it grammatically correct to start a sentence with "one thing"?
Yes, it is grammatically correct. Starting a sentence with "one thing" is a common way to introduce a specific idea or consideration.
What's the difference between "one thing" and "the main thing"?
"One thing" introduces a single point, while "the main thing" emphasizes the most important point among several.
Editing plus AI, all in one place.
Stop switching between tools. Your AI writing partner for everything—polishing proposals, crafting emails, finding the right tone.
Table of contents
Usage summary
Human-verified examples
Expert writing tips
Linguistic context
Ludwig's wrap-up
Alternative expressions
FAQs
Source & Trust
88%
Authority and reliability
4.5/5
Expert rating
Real-world application tested