unknown length of time

USAGE SUMMARY

"unknown length of time" is correct and usable in written English.
You can use it to refer to an amount of time that is not known or specified. For example: They have been away for an unknown length of time.

✓ Grammatically correct

News & Media

Science

Wiki

Human-verified examples from authoritative sources

Exact Expressions

9 human-written examples

We call that unknown length of time the "gap," when we'll be on our own, living nearly as if we were in the Stone Age.

The New Yorker

But for an unknown length of time, at least one exit node, based in Russia, has been silently altering programs downloaded through Tor, according to Josh Pitts, a security researcher for Leviathan Security.

The Guardian - Tech

The city's deputy police chief for homeland security, Kathleen Suey, said the man had been staying in the room where the ricin was found for an unknown length of time and was still renting the room when the substance was discovered.

The New York Times

They are released from a variety of cells, circulate in the blood for an unknown length of time and come to rest on endothelial surfaces.

Clinical and Translational Medicine

There are no direct sewage lines into the lagoon facility, so sewage is aged for an unknown length of time in septic tanks before hauling by septic trucks to the lagoon.

Chemistry Central Journal

Detectable inflammation may persist for an unknown length of time without persistent infection, and persistent infection may not result in persistent NGU [ 15, 46– 46].

BMC Infectious Diseases

Human-verified similar examples from authoritative sources

Similar Expressions

50 human-written examples

It also shows that potentially deadly steel service-box lids, manhole covers and lampposts existed for unknown lengths of time at some of the city's busiest intersections, just inches from thousands of daily passers-by.

The New York Times

Women with an unknown length of first treatment but known length of second treatment within a year were assigned the median length observed among women who had multiple treatments within a year for the unknown length.

BMC Pregnancy and Childbirth

"In the past, we've had a dip and then recovery, but now we're in unknown territory about the length of time people are going to have to cope with debt, job insecurity, pressure from work and the mounting cost of childcare.

The Guardian

21 (1.3%) of 1611 reported an immigration status of political asylum seeker or refugee (15 men, 5 women, 1 unknown; mean age 28.82 years [SD 13.02]; mean length of time in the UK 3.72 years [SD 2.27]).

BMC Health Services Research

However, the extent to which hybridization results in the transfer of genetic material across the species boundary (introgression) remains unknown in many systems, as does the length of time after initial divergence that the species boundary remains porous to such gene flow.

BMC Evolutionary Biology

Expert writing Tips

Best practice

When using "unknown length of time", consider if providing a range or estimate, even if approximate, would be more helpful to your audience. For example, instead of saying "the project will take an unknown length of time", you could say "the project is expected to take several months".

Common error

Avoid using "unknown length of time" in sentences where the lack of specific timeframe weakens the statement. Instead, try to quantify or qualify the time period to provide more meaningful information. E.g., avoid "The effects may last an unknown length of time" and say "The effects are expected to be long-lasting".

Linguistic Context

The phrase "unknown length of time" functions as an adjectival phrase modifying a noun, typically referring to a process, event, or state. Ludwig AI indicates it is grammatically sound. It indicates an absence of specific information regarding duration.

Expression frequency: Uncommon

Frequent in

News & Media

33%

Science

50%

Wiki

17%

Less common in

Formal & Business

0%

Encyclopedias

0%

Social Media

0%

Ludwig's WRAP-UP

The phrase "unknown length of time" is a grammatically correct and usable expression, as confirmed by Ludwig AI, that indicates uncertainty about a duration. While versatile, it appears most frequently in scientific and news contexts. When using this phrase, consider whether providing an estimate would offer more clarity. Alternatives like "unspecified duration" or "indefinite period" can sometimes offer a more concise way to convey the same meaning. While the phrase is valid, it is important to remember not to be vague and to use qualifiers when possible. The phrase's neutral register makes it appropriate for diverse writing styles.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

indefinite duration

Uses "indefinite" which is a direct synonym for "unknown".

unspecified timeframe

Replaces "length" with "timeframe", keeping the meaning intact while altering the phrasing.

uncertain duration

Replaces "unknown" with "uncertain", conveying a similar meaning of ambiguity.

unspecified duration

Replaces "length of time" with a single word, making it more concise.

undetermined period

Uses "period" instead of "length of time", implying a broader sense of time.

unquantified time frame

More formal and technical, using "quantified" and "frame" instead of "length".

uncalculated duration

Emphasizes that the time has not been calculated or estimated.

unfixed period

Highlights the lack of a set or established time.

unestablished timeframe

Similar to "unfixed period", emphasizing the lack of establishment.

unforeseen timeframe

Focuses on the unexpected nature of the time period.

FAQs

How can I use "unknown length of time" in a sentence?

You can use "unknown length of time" to describe a situation where the duration is not yet determined, such as "They will be conducting tests for an "unknown length of time"".

What's a more concise way to express "unknown length of time"?

Alternatives include "unspecified duration", or "indefinite period", depending on the context.

Is it better to give an estimate rather than saying "unknown length of time"?

In many cases, providing an estimate, even if approximate, is more helpful and informative than simply stating an "unknown length of time". However, if no estimation is possible, then the phrase is appropriate.

What does "unknown length of time" imply?

It suggests uncertainty about how long something will last or take, indicating that the duration is not predetermined or predictable.