Use the Correct Plural Form
Lesson 18 of 20 Thesis Editing Tips
From the Examiner’s Desk
“I frequently examine theses in which years of excellent research are obscured by weak writing.”
Many writing guides focus on grammar.
This lesson focuses on readability.
Its purpose is to help readers understand your ideas more quickly and with less effort.
As a PhD examiner and thesis editor, I often notice grammar mistakes before I begin evaluating the research itself.
One of the most common is the incorrect plural form of scientific and academic terms.
Although these mistakes rarely change the meaning of a sentence, they immediately affect the professional impression your thesis creates.
Using the correct singular and plural forms demonstrates attention to detail and familiarity with the language of your discipline.
Why Correct Plural Forms Matter
Many scientific and academic words come from Latin or Greek.
As a result, they do not always follow the normal English rule of simply adding -s.
Learning the correct forms helps your writing sound accurate and professional.
Fortunately, many of these words appear repeatedly throughout a thesis, so once you learn them, they become easy to remember.
Common Examples
Instead of writing:
❌ one criteria
write:
✅ one criterion
❌ several criterions
✅ several criteria
❌ one phenomenon
✅ several phenomena
❌ one analysis
✅ several analyses
❌ one hypothesis
✅ several hypotheses
❌ one bacterias
✅ many bacteria
❌ one datum
✅ data*
❌ one medium
✅ media
*In modern scientific writing, data is often treated as a collective noun, although some journals still distinguish between datum (singular) and data (plural). Always follow your university’s or journal’s style guide.
Examples from Academic Writing
Example 1
✅ Several bacteria were isolated from the samples.
Not:
❌ Several bacterium were isolated from the samples.
Example 2
✅ Three criteria were used to evaluate the intervention.
Remember:
• one criterion
• several criteria
Example 3
✅ The analyses confirmed the original hypothesis.
Notice the difference:
• one analysis
• several analyses
Example 4
✅ Several phenomena were observed during the experiment.
Again:
• one phenomenon
• several phenomena
These distinctions may seem small, but they immediately improve the accuracy and professionalism of your writing.
Other Frequently Confused Scientific Terms
Many disciplines also use words such as:
• index → indices (or indexes, depending on the discipline)
• appendix → appendices
• matrix → matrices
• vertex → vertices
Some scientific fields accept more than one plural form.
If your university or target journal provides guidance, always follow its preferred style.
💬 WhatsApp with Dr Anastasia Apostolides (reasonable hours)
Why Examiners Notice This
Scientific terminology forms part of the language of research.
Incorrect singular or plural forms interrupt the flow of reading and suggest that the thesis has not been carefully proofread.
Using the correct forms demonstrates precision, care and familiarity with your discipline.
Practical Editing Strategies
Before submitting your thesis:
• Make a list of technical terms you use repeatedly.
• Check whether any have irregular plural forms.
• Keep your own glossary of frequently used scientific words.
• Verify unfamiliar terms in a reputable scientific dictionary or your discipline’s style guide.
This takes only a few minutes but prevents many avoidable errors.
Quick Editing Checklist
Before submitting your thesis, ask yourself:
✓ Have I checked the singular and plural forms of technical terms?
✓ Are my verbs consistent with singular and plural nouns?
✓ Have I used scientific terminology consistently throughout the thesis?
✓ Have I checked unfamiliar words against a reliable source?
✓ Would an examiner recognise these forms as correct?
Key Takeaway
Scientific writing depends on precision.
Using the correct plural form is a small detail that makes a significant difference to the professionalism of your thesis.
Master the terminology of your discipline and your writing will immediately appear more polished and authoritative.
Small details often create the strongest first impression.
Need Professional Thesis Editing?
If you would like an experienced PhD examiner to review your thesis before submission, I’d be happy to help.
Whether you need a complete thesis edit, advice on improving clarity or feedback on a proposal, feel free to get in touch.
Dr Anastasia Apostolides
PhD Examiner • Thesis Editor • Proposal & Academic Consultant
Helping Master’s, MBA, DBA and PhD students write with clarity and confidence.
💬 WhatsApp with Dr Anastasia Apostolides (reasonable hours)
📧 Email: info@uedit.org
📍 uedit.org
Continue Learning
This article is part of the 20 Thesis Editing Tips series.
Continue to the next lesson or explore the complete collection of free thesis resources to strengthen every stage of your academic writing.