Are you getting them right?

I know this looks like something you’ve worked through ages ago when you were in primary school, and it mostly is; with some exceptions. English plurals might seem simple at first—just add "s" or "es" and you're done, right? But when you dig deeper, some words break the mold and leave even top-tier English learners (and sometimes native speakers) scratching their heads.

If you're aiming for a high score in IELTS or the General Paper, familiarising yourself with these for the written exams do help. At that level, you will not only be presenting a sophisticated essay, you will also be making sure you don’t give the examiner the satisfaction of catching you out on minor errors.

1. Crisis → Crises: Words of Greek origin often change "is" to "es."

2. Phenomenon → Phenomena: Another tricky Greek word, where singular and plural forms don’t end in “s.”

3. Medium → Media: Common in discussions about communication, but misused when referring to an artist's tools or a spiritual medium.

4. Datum → Data: Many confuse "data" as singular; it’s the plural of "datum."

5. Alumnus → Alumni: Commonly used in education, "alumni" refers to a group of male graduates or a mixed group, while alumnae refers to female graduates only—often confused!

6. Matrix → Matrices: Used in math, science, and even business. People mistakenly use "matrixes" when the Latin plural "matrices" is the correct form.

7. Basis → Bases: Not to be confused with the plural of "base." "Bases" is the plural for "basis" when referring to underlying principles or reasons.

8. Stimulus → Stimuli: A word found in psychology and biology, where the plural "stimuli" replaces "stimulus," but many mix this up.

9. Curriculum → Curricula: In academic settings, "curricula" is used for multiple sets of courses, though "curriculums" is sometimes heard in casual speech.

10. Radius → Radii: From mathematics, "radii" refers to the plural of the line extending from the center to the edge of a circle.

11. Appendix → Appendices: Often used in academic contexts, "appendices" refers to more than one section of added material.

12. Index → Indices: While "indexes" is common in everyday language, "indices" is the correct plural in mathematical and scientific fields.

13. Corpus → Corpora: Used in linguistics or science to refer to multiple bodies of text or data.

14. Cactus → Cacti: One of those surprising Latin plurals, though "cactuses" is often accepted.