Irregular Plural Nouns Worksheet - ALL ESL - Free Printable

Let’s go through each word one by one and find its correct irregular plural form. I’ll think carefully about each to make sure I get them right.

1. Man → The plural is not “mans” — it changes completely: Men
2. Foot → Not “foots” — it becomes Feet
3. Tooth → Not “tooths” — it becomes Teeth
4. Mouse → Not “mouses” (unless talking about computer mice, but here we mean the animal) → Mice
5. Person → Can be “persons” in legal contexts, but the common irregular plural is People
6. Deer → This one doesn’t change at all! Singular and plural are the same → Deer
7. Child → Not “childs” — it becomes Children
8. Woman → Like “man”, it changes vowel sound → Women
9. Quiz → Ends in -z, so we add -es → Quizzes (Note: this is regular, but often grouped with irregulars because of spelling change)
→ Wait — actually, “quiz” is technically a regular noun that just follows the rule for words ending in consonant + y or z? No — quiz ends in ‘z’, so we double the ‘z’ and add ‘es’. But is it considered *irregular*? Hmm… In many school worksheets, they include it because the spelling changes noticeably. Let’s keep it as Quizzes.
→ Actually, let me double-check: Some sources say “quiz” is regular (just add -es), but since the worksheet includes it under “irregular”, we’ll go with the expected answer: Quizzes
10. Tuna → Fish like tuna usually don’t change in plural → Tuna (same as singular)
→ Or sometimes “tunas” if referring to types, but generally Tuna is accepted as plural too. Since it’s listed here, likely expecting Tuna

Now the second column:

11. Bacterium → From Latin/Greek, plural is Bacteria
12. Crisis → Changes -is to -es → Crises
13. Series → Same in singular and plural → Series
14. Index → Can be “indexes” (regular) or “indices” (irregular, from Latin). In academic/scientific contexts, Indices is preferred. Since this is an “irregular plural” worksheet, we’ll use Indices
15. Fungus → Plural is Fungi (from Latin)
16. Cactus → Plural can be “cactuses” or “cacti”. Again, for irregular, we use Cacti
17. Axis → Like crisis, changes -is to -es → Axes
18. Datum → From Latin, plural is Data (though now “data” is often used as singular too, but traditionally plural of datum)
19. Analysis → Changes -is to -es → Analyses
20. Formula → Can be “formulas” or “formulae”. For irregular, we use Formulae (Latin-style)

Wait — let me verify a few tricky ones again:

- Quiz → Quizzes (yes, standard)
- Tuna → Tuna (yes, fish often unchanged)
- Index → Indices (yes, for irregular)
- Formula → Formulae (yes, though formulas is also correct, but worksheet wants irregular)

Okay, I’m confident now.

Final Answer:
1. Men
2. Feet
3. Teeth
4. Mice
5. People
6. Deer
7. Children
8. Women
9. Quizzes
10. Tuna
11. Bacteria
12. Crises
13. Series
14. Indices
15. Fungi
16. Cacti
17. Axes
18. Data
19. Analyses
20. Formulae