once every 3 weeks

USAGE SUMMARY

The phrase "once every 3 weeks" is correct and usable in written English.
It can be used to describe an event or action that occurs at three-week intervals. Example: "The team meets once every 3 weeks to discuss project updates and progress."

✓ Grammatically correct

Science

News & Media

Human-verified examples from authoritative sources

Exact Expressions

59 human-written examples

Each ship is visited once every 3 weeks by an inspection crew.

The New Yorker

Both agents were administered once every 3 weeks for two total cycles, each at a dose of 75 mg/m2.

EJNMMI Research

Both drugs are administered via intravenous infusion once every 3 weeks until evidence of disease progression, unacceptable toxicity, noncompliance, or patient's consent withdrawal.

Clinical Lung Cancer

When this combination is indicated by the doctors, the procedure usually is done in four doses separately, once every 3 weeks.

Progress in Biomaterials

A single-dose of 850 1000 mg/m [2] administered once every 3 weeks was referenced as standard therapy with response rate of 13 20 % of patients [12, 13, 14].

International Nano Letters

infusion once every 3 weeks.

British Journal of Cancer

Both chemotherapy regimens were given once every 3 weeks.

British Journal of Cancer

The treatment was administered once every 3 weeks.

British Journal of Cancer

The patients received ipilimumab once every 3 weeks for 4 doses and nivolumab once every 3 weeks for 8 doses concurrently.

BioMed Research International

Most IRAEs occurred during induction (initial four doses given once every 3 weeks).

Cancer Management and Research

Human-verified similar examples from authoritative sources

Similar Expressions

1 human-written examples

Phase II single-agent studies are under way in a number of different tumour types investigating the once-every-3-weeks and daily-for-5-days schedules.

British Journal of Cancer

Expert writing Tips

Best practice

When writing for a general audience, consider using "every three weeks" instead of "once every 3 weeks" for better readability.

Common error

Avoid mixing weekly and monthly timeframes in the same context. For example, don't say "once every 3 weeks, which is about once a month" unless you're approximating, as the math isn't precise.

Linguistic Context

The phrase "once every 3 weeks" functions as an adverbial phrase of frequency, modifying a verb by specifying how often an action occurs. As Ludwig AI confirms, this phrase is both correct and usable.

Expression frequency: Very common

Frequent in

Science

95%

News & Media

3%

Formal & Business

2%

Less common in

Academia

0%

Encyclopedias

0%

Wiki

0%

Ludwig's WRAP-UP

In summary, the phrase "once every 3 weeks" serves as a clear and common adverbial phrase indicating the frequency of an event. Ludwig AI validates its correct usage. While grammatically sound, contexts influence preferred alternatives such as "every three weeks" for general audiences. Predominantly appearing in scientific contexts, "once every 3 weeks" is vital for specifying precise schedules, particularly in medical or research settings. When you need clarity regarding schedules, dosing or planning, consider this phrase and its similar options.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

every three weeks

This is a more concise and common alternative, using the determiner 'every' instead of 'once every'.

triweekly

This is a single-word adjective that directly means 'occurring every three weeks'.

at three-week intervals

This option uses a noun phrase to describe the frequency, emphasizing the interval between occurrences.

every three weeks on a recurring basis

Adds emphasis on the repetitive nature of the event or action.

one time in three weeks

Rephrases the frequency with a focus on the single occurrence within the three-week period.

a single time every three weeks

Similar to the previous option, highlighting the singularity of the event within the interval.

each three weeks

Focuses on the three-week period as a unit in which the event happens.

on a three-weekly basis

Uses the 'on a ... basis' structure to express the frequency.

at a frequency of once every three weeks

Formal and explicit phrasing for clearly stating the frequency.

every 21 days

Expresses the interval in terms of days rather than weeks.

FAQs

What does "once every 3 weeks" mean?

The phrase "once every 3 weeks" means that something happens one time within a period of three weeks, and then repeats at similar three-week intervals.

How can I rephrase "once every 3 weeks"?

You can use alternatives like "every three weeks" or "triweekly" to convey the same meaning.

Is it better to say "every three weeks" or "once every 3 weeks"?

Both phrases are correct. "Every three weeks" is generally considered more concise and common, while "once every 3 weeks" provides a bit more emphasis on the single occurrence.

Why is the phrase "once every 3 weeks" often used in medical contexts?

In medicine, specifying the frequency of treatments or dosages is crucial for clarity and adherence. "Once every 3 weeks" clearly defines a regimen's schedule.