Focuses or Foci - What is The Plural of "Focus"?

It’s not very common to see the plural form of “Focus”, which means that one can often get confused as to what word accurately conveys the plural: Is it “Focuses” or “Foci”? The following article clarifies which form should be used, and if there’s any difference between them at all.

Focuses or Foci – What is The Plural of “Focus”?

Both “Focuses” and “Foci” are valid ways to pluralize “Focus”, and whichever one you use depends on personal preference more than anything else. Both are grammatically correct, albeit alternate, ways of creating the plural form of “Focus”, and different people will have a preference for either one.

According to The Cambridge Dictionary, both “Focuses” and “Foci” are correct, and can be used to pluralize “Focus”.

Both forms are also generally found in highly technical and scientific contexts, and therefore whichever one tends to be used is usually a matter of the specific field’s custom and the writer’s preference.

Another alternative, for readability, would be to rephrase the sentence with a synonym of focus that has an easier plural form, such as “Focal point” or “Target”.

Is “Focuses” Or “Foci” Used The Most?

Data compiled by the Google Ngram Viewer suggests that “Focuses” is vastly more utilized than “Foci” in literature in the English language.

However, this information should not be taken at face value. “Focuses” is also the present simple tense of the verb “To Focus”, and this data is unable to discriminate between uses of the verb tense and the plural of “Focus”.

This fact could help explain the seemingly disproportionate disparity between uses of “Focuses” and “Foci” in literature.

In spite of all that, the fact remains that “Focuses” sees a lot more use than “Foci”, in spite of “Foci” being an older term, as it’s first recorded in the chart in the year 1800.

“Focuses”, however, first started gaining popularity in the 1920s, and by the mid-1960s it was bursting in sudden popular use, vastly overtaking “Foci” as the more popular term.

Should I Use “Focuses” Or Foci” In The UK?

The data compiled by the Google Ngram Viewer actually indicates that in the United Kingdom, the vastly more popular choice is “Focuses”.

The chart has a few oddities, such as a spike in use of “Foci” at the beginning of the 1910s, and it also presents “Focuses” exploding in popularity in the mid-1960s.

It’s also worth noting that according to the data on the chart, “Focuses” had a near constant rise in popularity since the 1960s, with the exception of 2005 to 2011, in which the use of the term decreased.

Should I Use “Focuses” Or Foci” In The US?

Information collected by the Google Ngram Viewer clearly outlines that “Focuses” is a far more popular option than “Foci” in the United States.

The graph showcases the fact that “Foci” was actually more popular than “Focuses” as a term for decades, up until the beginning of the 1960s, in which “Focuses” became the more common term.

“Foci” hit its peak popularity in the year 1920, after which it slightly decreased in popularity. The term has stayed relatively stable in popularity since, with “Focuses” growing more popular than it every year.

Examples Of How To Use The Plural Of Focus In A Sentence

Here are some example sentences to showcase how you can use both alternate plural forms of “Focus”:

The focuses of that investigation were completely different at the end of the day.
This paper’s foci are mainly the different planets of the solar system, and their moons.
I disagree with his philosophical approach because his different focuses are strange.
The mining operation had several foci, including discovering more of this strange mineral.
His solution has five different focuses, each centered on a different core pillar.
The filmmaker had many foci, but her main one was getting her next movie greenlit.
The prosecution’s approach has five focuses, and four of those are inaccurate.
Of the seven foci that I decided on for this thesis, this one was my favorite.
Networking was one of my main focuses at the corporate pool party last month.
None of these foci work, conceptually.

Foci” And “Focuses” – Synonyms

Focal points
Spotlights
Targets
Centers
Cores