every fourth day

USAGE SUMMARY

The phrase "every fourth day" is correct and usable in written English.
It can be used to describe an event or action that occurs once every four days. Example: "The medication should be taken every fourth day to ensure its effectiveness."

✓ Grammatically correct

Science

News & Media

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

The newly transplanted seedlings were covered with humidity domes for two days and thereafter watered every fourth day.

BMC Genomics

A prisoner sentenced to detention ("Arrest") in one of these cells gets nothing to eat on the first day, then bread and water for three days, and a hot meal every fourth day.

The Guardian

Initially, streaking was done on every fourth day, and then the time interval was increased to 15 days.

International Journal of Recycling of Organic Waste in Agriculture

Fresh medium was added every fourth day and the number of neurospheres was assessed after 14 days.

eLife

Every fourth day they work as mechanics in one of two garages on either side of the river.

The New York Times

Every fourth day they get the cafeteria-style food that the American soldiers at the base receive every day.

The New York Times

One principal, Marilyn MercadofBelvin of the John Paulding School, has let Mr. Smith know that students need Spanish twice a week, not just every fourth day.

The New York Times

In classes where Spanish is taught as a foreign language, a specialist visits the second, third and fourth grades every fourth day for a 40-minute lesson.

The New York Times

Almost a 100,000 residents in Tikamgarh get piped water for just two hours every fourth day, while municipal authorities have ordered new bore wells to be dug to meet demand.

The Guardian

The parasitemia culture was maintained in between 1 and 5% and routinely sub-culturing was performed on every fourth day.

Chemistry Central Journal

The drug topotecan was given according to an intermittent (every fourth day, four times) or daily (qd×5/weekly×5−10 weeks; only orally) schedule.

European Journal of Cancer

Expert writing Tips

Best practice

To avoid ambiguity, clarify whether the count includes the starting day. For instance, state: "Administer the drug on day 1, then again "every fourth day" (days 5, 9, 13, etc.)."

Common error

A common mistake is failing to clarify whether the initial day is included in the count. To avoid confusion, specify the exact dates or intervals. Example: "Not 'Begin treatment "every fourth day",' but 'Begin treatment on July 23rd, then continue on July 27th, July 31st, and so on'."

Linguistic Context

The phrase "every fourth day" functions as an adverbial of frequency, modifying a verb by specifying how often an action occurs. As confirmed by Ludwig AI, it is a correct and usable phrase in written English.

Expression frequency: Very common

Frequent in

Science

63%

News & Media

33%

Wiki

4%

Less common in

Formal & Business

0%

Encyclopedias

0%

Reference

0%

Ludwig's WRAP-UP

The phrase "every fourth day" is a common and grammatically sound adverbial phrase used to describe the frequency of an event, occurring once every four days. Ludwig AI confirms its correctness and usability. Predominantly found in scientific and news contexts, it specifies the regularity of an action, like administering medication or watering plants. To ensure clarity, define the starting point when scheduling tasks. Common alternatives are "once every four days" and "at four-day intervals". Avoid confusion by clarifying if the initial day is included in the counting, and consider context-appropriate synonyms for better writing. Avoid using "every four day" as it is grammatically incorrect.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

once every four days

This alternative explicitly states the frequency of occurrence using the word 'once'.

every 96 hours

This alternative specifies the interval in terms of hours instead of days, providing a more precise measure of time.

quadridaily

This is a less common, single-word adjective that means occurring every four days.

at four-day intervals

This alternative emphasizes the consistent spacing between occurrences.

on a four-day cycle

This alternative implies a repeating pattern with a duration of four days.

every three days

Alters the frequency to a shorter interval.

every five days

Alters the frequency to a longer interval.

at four day period

Specifies more explicitly that the recurrency is over a period of four days.

each fourth day

Replaces 'every' with 'each' to emphasize individual instances.

four days apart

This phrase focuses on the separation between occurrences, rather than the recurrence itself.

FAQs

How can I use "every fourth day" in a sentence?

You can use "every fourth day" to describe recurring events or actions. For example, "The plants need to be watered "every fourth day" to maintain proper moisture levels."

What is another way to say "every fourth day"?

Alternatives include "once every four days", "at four-day intervals", or "quadridaily", depending on the desired level of formality.

Is it correct to say "every four day" instead of "every fourth day"?

While "every four day" might be understood, it is grammatically incorrect. The ordinal number "fourth" specifies the recurring interval. Saying "every four day" is a mistake similar to saying “every three day” instead of “every third day”.

What's the difference between "every third day" and "every fourth day"?

"Every third day" means something occurs once every three days, while "every fourth day" means it occurs once every four days. The interval is different, affecting the frequency of the action or event. See also: "every third day".