Irregular Plural Nouns Worksheets - 15 Worksheets Library - Free Printable

Let's solve the worksheet titled "Irregular Plural Nouns" step by step. The task is to write the correct plural form for each given noun.

---

Understanding Irregular Plural Nouns

Many English nouns form their plurals irregularly — they don't follow the standard rules (like adding *-s* or *-es*). Instead, they have unique plural forms that must be memorized.

---

Solutions with Explanations

1. zero → zeros
*Explanation:* Regular plural; add *-s*. Although "zero" is sometimes used as an irregular noun in certain contexts (e.g., "zeroes"), "zeros" is more common and accepted.

2. tornado → tornadoes
*Explanation:* Add *-es* (common for words ending in *-o* that are not of Latin origin). Also acceptable: "tornados".

3. pimento → pimentos
*Explanation:* Words ending in *-o* from Spanish often take *-s* for plural. "Pimentos" is the standard plural.

4. analysis → analyses
*Explanation:* This is a Greek-derived word. Plural is formed by changing *-is* to *-es*.

5. oasis → oases
*Explanation:* Another Greek-origin word. Plural is formed by changing *-is* to *-es*.

6. ellipsis → ellipses
*Explanation:* Same pattern as "analysis". Change *-is* to *-es*.

7. vita → vitae
*Explanation:* Latin word meaning "life". The plural is "vitae", pronounced *vy-tay*.

8. index → indices
*Explanation:* Latin origin. Plural is *indices* (pronounced *in-dih-si*), though *indexes* is also acceptable in modern usage.

9. nebula → nebulae
*Explanation:* Latin word. Plural is *nebulae*, though *nebulae* is more formal; *nebulae* is preferred in scientific contexts.

10. volcano → volcanoes
*Explanation:* Add *-es* for words ending in *-o* from non-Latin origins. "Volcanos" is less common but sometimes used.

11. halo → haloes
*Explanation:* Can be spelled *halos* or *haloes*. Both are acceptable, but *haloes* is traditional.

12. tomato → tomatoes
*Explanation:* Add *-es* because it ends in *-o* and is not a Latin word.

13. diagnoses → diagnoses
*Explanation:* Wait! This is already plural. But the instruction says “Write the plural for each noun.” So we need to find the singular form first? No — the list includes “diagnoses” as number 13, which is already plural. That seems like a mistake.

However, looking at the context, perhaps this is a typo or error in the worksheet. Let’s double-check:

- The noun listed is diagnoses, which is the plural of diagnosis.
- But the prompt says: “Write the plural for each noun.”

So if the noun is diagnosis, then plural is diagnoses.

But here, diagnoses is listed as the noun. So what is its plural?

→ Actually, diagnoses is already plural. There is no such plural form as "diagnosese" or "diagnosises".

✔ Conclusion: This appears to be a mistake. It should probably be diagnosis instead of diagnoses.

But assuming the worksheet meant to say diagnosis, then:
→ diagnosis → diagnoses

But since the noun listed is diagnoses, and it's already plural, perhaps it's a trick question?

However, since the rest of the list has singular nouns, likely this is a typo, and the intended noun was diagnosis.

But let’s proceed with the assumption that the noun is diagnosis, so the plural is diagnoses.

But wait — the blank is next to diagnoses, so we’re being asked: What is the plural of diagnoses?

✘ That doesn’t make sense.

So the only logical conclusion is: The noun listed is incorrect.

Therefore, we will assume it's a typo and the intended noun was diagnosis.

So: diagnosis → diagnoses

But since the worksheet says “diagnoses”, we can’t write a plural of it. So maybe it’s asking for the plural of the singular form, which is missing.

Alternatively, perhaps it’s just testing recognition: diagnoses is already plural.

But since the directions say “write the plural”, and the noun is already plural, this is confusing.

Let’s move on and come back.

⚠️ Likely error: Should be diagnosis → diagnoses

But for now, we'll treat it as diagnosis → diagnoses

14. crisis → crises
*Explanation:* Greek origin. Plural is *crises* (change *-is* to *-es*).

15. analysis → analyses
*Explanation:* Same as #4. Already covered.

16. larva → larvae
*Explanation:* Latin word. Plural is *larvae* (pronounced *lair-vee*).

17. erratum → errata
*Explanation:* Latin word meaning "error". Plural is *errata* (pronounced *er-ra-ta*).

18. alumna → alumnae
*Explanation:* Latin word meaning "female graduate". Plural is *alumnae* (pronounced *al-um-nee*). For males, it's *alumni*.

---

✔ Final Answer Key:

| Number | Noun | Plural Form |
|--------|-------------|------------------|
| 1 | zero | zeros |
| 2 | tornado | tornadoes |
| 3 | pimento | pimentos |
| 4 | analysis | analyses |
| 5 | oasis | oases |
| 6 | ellipsis | ellipses |
| 7 | vita | vitae |
| 8 | index | indices |
| 9 | nebula | nebulae |
| 10 | volcano | volcanoes |
| 11 | halo | haloes |
| 12 | tomato | tomatoes |
| 13 | diagnoses | (Error) → should be diagnosis → diagnoses |
| 14 | crisis | crises |
| 15 | analysis | analyses |
| 16 | larva | larvae |
| 17 | erratum | errata |
| 18 | alumna | alumnae |

---

🛠️ Note on #13:

- The word diagnoses is already the plural form of diagnosis.
- So if the noun listed is diagnoses, then its plural would be... well, there isn't one. You don't make a plural of a plural.
- Therefore, this is likely a typo in the worksheet. It should read diagnosis instead of diagnoses.

✔ Corrected version:
13. diagnosis → diagnoses

---

✔ Final Answers to Write in Blank Spaces:

1. zeros
2. tornadoes
3. pimentos
4. analyses
5. oases
6. ellipses
7. vitae
8. indices
9. nebulae
10. volcanoes
11. haloes
12. tomatoes
13. diagnoses *(if original is "diagnosis")*
14. crises
15. analyses
16. larvae
17. errata
18. alumnae

---

Summary:

Most of these are Latin or Greek-derived words with irregular plural forms. The key is recognizing patterns:
- -is → -es: analysis → analyses
- -on → -a: phenomenon → phenomena (not on list)
- -us → -i: focus → foci (not on list)
- -a → -ae: alumna → alumnae
- -um → -a: erratum → errata
- -o → -oes: tomato → tomatoes
- -o → -s: zero → zeros

Let me know if you'd like a printable version or flashcards!