Irregular Plural Nouns worksheet with 20 exercises to convert singular nouns to their irregular plural forms.

Task: Convert each singular noun to its irregular plural form.

#### Solution:

Here is the completed list of irregular plural nouns:

1. Man → Men
2. Foot → Feet
3. Tooth → Teeth
4. Mouse → Mice
5. Person → People
6. Deer → Deer
7. Child → Children
8. Woman → Women
9. Quiz → Quizzes
10. Tuna → Tuna
11. Bacterium → Bacteria
12. Crisis → Crises
13. Series → Series
14. Index → Indices
15. Fungus → Fungi
16. Cactus → Cacti
17. Axis → Axes
18. Datum → Data
19. Analysis → Analyses
20. Formula → Formulae

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Explanation:

Irregular plural nouns do not follow the standard rule of adding "-s" or "-es" to form the plural. Instead, they have unique forms that must be memorized. Here are some patterns and explanations for the answers:

1. Man → Men: The plural form changes the vowel sound.
2. Foot → Feet, Tooth → Teeth: These words change both the vowel and add a different ending.
3. Mouse → Mice: The "o" changes to "i," and the ending becomes "-ce."
4. Person → People: This is an entirely different word for the plural.
5. Deer → Deer: Some nouns remain the same in both singular and plural forms.
6. Child → Children: The plural form has a completely different structure.
7. Woman → Women: Similar to "man," the vowel changes.
8. Quiz → Quizzes: While this follows a common pattern (-z becomes -zes), it is still considered irregular because it doesn't follow the standard "-s" rule.
9. Tuna → Tuna: Like "deer," it remains the same.
10. Bacterium → Bacteria: Many scientific terms ending in "-ium" change to "-ia."
11. Crisis → Crises: Words ending in "-sis" often change to "-ses."
12. Series → Series: Some nouns, especially those borrowed from Latin or Greek, remain the same.
13. Index → Indices: Words ending in "-ex" often change to "-ices."
14. Fungus → Fungi: Borrowed from Latin, these words often use Latin plural forms.
15. Cactus → Cacti: Similar to "fungus," it uses a Latin plural form.
16. Axis → Axes: Words ending in "-is" often change to "-es."
17. Datum → Data: Borrowed from Latin, where "datum" is singular and "data" is plural.
18. Analysis → Analyses: Words ending in "-sis" often change to "-ses."
19. Formula → Formulae: Borrowed from Latin, where "-a" changes to "-ae."

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Final Answer:

\[
\boxed{
\begin{array}{ll}
1. \text{Man} \to \text{Men} & 11. \text{Bacterium} \to \text{Bacteria} \\
2. \text{Foot} \to \text{Feet} & 12. \text{Crisis} \to \text{Crises} \\
3. \text{Tooth} \to \text{Teeth} & 13. \text{Series} \to \text{Series} \\
4. \text{Mouse} \to \text{Mice} & 14. \text{Index} \to \text{Indices} \\
5. \text{Person} \to \text{People} & 15. \text{Fungus} \to \text{Fungi} \\
6. \text{Deer} \to \text{Deer} & 16. \text{Cactus} \to \text{Cacti} \\
7. \text{Child} \to \text{Children} & 17. \text{Axis} \to \text{Axes} \\
8. \text{Woman} \to \text{Women} & 18. \text{Datum} \to \text{Data} \\
9. \text{Quiz} \to \text{Quizzes} & 19. \text{Analysis} \to \text{Analyses} \\
10. \text{Tuna} \to \text{Tuna} & 20. \text{Formula} \to \text{Formulae} \\
\end{array}
}
\]