What are foreign word plurals?
Some words in English come from other languages, like Latin or Greek. These words often have special plural forms. We do not add -s or -es like normal English words. Instead, we use the plural form from the original language. This is important for correct English writing and speaking.
Common foreign word plurals
The most common foreign plurals are from Latin and Greek. "Data" is the plural of "datum." "Criteria" is the plural of "criterion." "Phenomena" is the plural of "phenomenon." These words are used in science, business, and academic English. You will see them often in professional writing.
Why learn these plurals?
Using correct foreign plurals makes you sound more professional and educated. In academic writing and formal English, these forms are expected. Many A1 learners ignore these words, but they appear in important contexts like medicine, science, and business communication.
Foreign Word Plurals at a Glance
| Singular | Plural | Origin | Note |
|---|---|---|---|
| datum | data | Latin | Data often treated as singular in everyday use |
| criterion | criteria | Greek | Criteria is plural; avoid "a criteria" |
| phenomenon | phenomena | Greek | Phenomena is plural; "a phenomena" is incorrect |
| analysis | analyses | Greek | –is → –es pattern (also: thesis/theses) |
| thesis | theses | Greek | –is → –es pattern |
| basis | bases | Greek | –is → –es pattern |
| index | indices / indexes | Latin | Indices = technical/math; indexes = general use |
| appendix | appendices / appendixes | Latin | Both forms accepted; appendices more formal |
| formula | formulae / formulas | Latin | Formulae = scientific; formulas = everyday |
| medium | media / mediums | Latin | Media = press/communications; mediums = psychics |
| curriculum | curricula / curriculums | Latin | –um → –a pattern; both forms accepted |
| symposium | symposia / symposiums | Latin/Greek | –um → –a pattern; both forms accepted |
| cactus | cacti / cactuses | Latin | –us → –i pattern; cactuses also widely accepted |
| nucleus | nuclei | Latin | –us → –i pattern; common in scientific writing |
| alumnus | alumni | Latin | Masculine form; alumna / alumnae = feminine |
| bacterium | bacteria | Latin | Bacteria is plural; "a bacteria" is incorrect |
| stratum | strata | Latin | –um → –a pattern; used in geology & sociology |
| tableau | tableaux / tableaus | French | –eau → –eaux pattern; both spellings accepted |
| bureau | bureaux / bureaus | French | –eau → –eaux pattern; both spellings accepted |
Examples
This data is very important for our study.
Formal · Plural noun from Latin
The criteria for the job are very strict.
Academic · Plural noun from Greek
These phenomena are difficult to explain.
Scientific · Plural noun from Greek
The analysis shows several interesting phenomena in the data.
Academic writing · Two foreign plurals together
What criteria did you use for your decision?
Business English · Question form
The collected data needs careful analysis.
Research · Common in scientific texts
When to use it
Science & Research
Scientists use these words every day when discussing experiments and observations.
"The phenomena we observed in the lab are very interesting."
Business & Work
Business professionals use these words in reports, meetings, and formal documents.
"Our selection criteria are fairness and experience."
Academic Writing
University students and teachers use foreign plurals in essays and research papers.
"The collected data suggest a new theory."
Signal words
data
criterion
criteria
phenomenon
phenomena
analysis
analyses
medium
media
radius
radii
Common Mistakes
✕
Wrong
The datas show interesting patterns.
✓
Correct
The data show interesting patterns.
Data is already plural. Never add -s to foreign plurals.
✕
Wrong
These criterias are important.
✓
Correct
These criteria are important.
Criteria is the plural form. Do not add -s.
✕
Wrong
The phenomenas are strange.
✓
Correct
The phenomena are strange.
Phenomena is already plural from Greek. No -s needed.
KEY TAKEAWAYS
What to Remember
- Some English words come from Latin or Greek and have special plural forms.
- Data is plural (datum is singular); criteria is plural (criterion is singular).
- Phenomena is plural of phenomenon; these words don't follow normal English plural rules.
- Don't add -s or -es to these foreign words; use their original language plurals.
- Common mistake: treating data, criteria, and phenomena as singular words in sentences.