used to know

USAGE SUMMARY

The phrase "used to know" is correct and usable in written English.
It is typically used to indicate a past state of knowledge or familiarity that no longer exists. Example: "I used to know how to play the piano, but I haven't practiced in years."

✓ Grammatically correct

News & Media

Academia

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

When people who used to know us see us, they're shocked.

The Guardian

People used to know us for the food and shopping.

The New York Times

Well, they used to know.

The Economist

Republicans used to know this.

The Economist

He used to know.

The New Yorker

I used to know it by memory.

The New York Times

You used to know how to write.

The New York Times

"Everybody used to know it," he pleaded.

The New York Times - Arts

Ray said, "I used to know everyone.

The New Yorker

I used to know everybody".

The New York Times

I used to know Jo.

The Guardian - Music

Expert writing Tips

Best practice

When using "used to know", ensure the context clearly indicates what or whom was known in the past and why that knowledge is no longer current. This adds clarity and prevents ambiguity.

Common error

Avoid using "used to know" when referring to something that is still known. Instead, use the present tense to indicate current knowledge.

Linguistic Context

The phrase "used to know" functions as a verb phrase indicating a past state of knowledge or familiarity that is no longer current. As Ludwig AI highlights, it denotes a past condition that has changed. Examples show its usage in various contexts, from personal relationships to general awareness.

Expression frequency: Uncommon

Frequent in

News & Media

67%

Academia

22%

Science

11%

Less common in

Formal & Business

0%

Encyclopedias

0%

Wiki

0%

Ludwig's WRAP-UP

In summary, "used to know" is a grammatically sound phrase used to express a past state of knowledge or familiarity that no longer exists. Ludwig AI confirms its correct usage, which is most common in news and media and academic contexts. While the phrase itself is neutral, careful attention should be paid to tense consistency and clarity regarding the object of knowledge. Consider alternatives like "once knew" or "was familiar with" for nuanced expression. When used correctly, "used to know" effectively conveys a contrast between past and present understanding.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

once knew

Focuses on the past familiarity without necessarily implying a complete loss of knowledge.

knew previously

Highlights that knowledge existed at an earlier time, but not currently.

was familiar with

Emphasizes the level of acquaintance or understanding in the past.

had knowledge of

Stresses the possession of information in the past.

used to be acquainted with

Similar to "used to know", but it refers to being personally familiar with someone.

at one time knew

Emphasizes that knowledge was present at a specific point in the past.

knew back then

Informal way to express past knowledge.

once recognized

Implies a past ability to identify or acknowledge someone or something.

had once learned

Implies a past action of acquiring information or a skill.

used to be aware of

Focuses on past awareness or consciousness of something.

FAQs

How can I use "used to know" in a sentence?

You can use "used to know" to express a past state of knowledge or familiarity that no longer exists. For example, "I "used to know" everyone in this town, but now it's changed so much".

What are some alternatives to "used to know"?

Alternatives include "once knew", "was familiar with", or "had knowledge of" depending on the specific context.

Is it correct to say "I use to know" instead of "I used to know"?

No, "I use to know" is grammatically incorrect. The correct form is "I "used to know"", with the "d" indicating past tense.

What is the difference between "used to know" and "knew"?

"Knew" simply indicates past knowledge. "Used to know" implies that the knowledge or familiarity existed regularly in the past but is no longer the case. For example, "I knew her" just states a past acquaintance, while "I "used to know" her" suggests we were once close but are not anymore.