Regular and Irregular Nouns

A regular noun makes its plural by adding -s or -es (cat → cats, box → boxes, city → cities). An irregular noun makes its plural some other way: by changing a vowel (man → men), adding -en (child → children), changing -f to -ves (knife → knives), keeping the same form (sheep → sheep) or using a Latin or Greek ending (cactus → cacti, crisis → crises).

The regular rules cover the vast majority of English nouns, so learners mainly need the short list of irregular ones. Here are the most common, then the rules in detail, mistakes and practice with answers.

The most common irregular plurals

Definition of Regular and Irregular Nouns

In English grammar, nouns are categorized as either regular or irregular based on how they form their plural forms. Understanding this distinction is crucial for correct grammar and clear communication.

Regular nouns form their plural by adding -s or -es to the end of the singular form. This is the most common and predictable way to pluralize nouns in English. For example, the singular noun “cat” becomes “cats” in the plural, and the singular noun “box” becomes “boxes” in the plural.

Irregular nouns, on the other hand, do not follow this simple rule. They form their plural in various ways, often involving changes to the internal vowel, the addition of different suffixes, or no change at all. These nouns require memorization and careful attention to detail. For example, the singular noun “child” becomes “children” in the plural, and the singular noun “mouse” becomes “mice” in the plural. Some irregular nouns, like “sheep,” have the same form in both singular and plural.

Regular Nouns

Regular nouns are the most common type of nouns in English, and they follow predictable rules for forming their plural forms. Mastering these rules is essential for building a solid foundation in English grammar.

Formation of Regular Plurals

The vast majority of English nouns are regular, meaning they form their plural by simply adding -s to the end of the singular form. However, there are a few variations to this rule, depending on the ending of the singular noun:

• Most nouns: Add -s to the end of the singular form. Examples: book → books, car → cars, table → tables.
• Nouns ending in -s, -ss, -sh, -ch, -x, or -z: Add -es to the end of the singular form. Examples: bus → buses, glass → glasses, dish → dishes, watch → watches, box → boxes, quiz → quizzes.
• Nouns ending in consonant + y: Change the -y to -i and add -es. Examples: baby → babies, city → cities, story → stories.
• Nouns ending in vowel + y: Simply add -s. Examples: boy → boys, day → days, toy → toys.
• Nouns ending in -o: For some nouns ending in -o, add -es. For others, just add -s. There is no definitive rule, but here are some guidelines:
  • Short forms and many words from Italian or Spanish add just -s: photo → photos (from photograph), piano → pianos, kilo → kilos, radio → radios, video → videos.
  • A small set of older, everyday words add -es: tomato → tomatoes, potato → potatoes, hero → heroes, echo → echoes, veto → vetoes.
  • However, there are exceptions to both of these guidelines. It’s best to consult a dictionary when in doubt.
• Nouns ending in -f or -fe: Most just add -s: chief → chiefs, roof → roofs, cliff → cliffs, belief → beliefs. About a dozen common ones change -f to -ves instead (leaf → leaves, knife → knives); because that is not the regular -s pattern, they are listed with the irregular nouns below. A few take either: scarf → scarves or scarfs, hoof → hooves or hoofs.

Examples of Regular Nouns

The following table provides a comprehensive list of regular nouns and their corresponding plural forms, categorized by the rule they follow.

Irregular Nouns

Irregular nouns are nouns that do not form their plural by simply adding -s or -es. They have unique plural forms that must be memorized.

Formation of Irregular Plurals

Irregular nouns form their plural in a variety of ways, including:

• Internal vowel change: The vowel sound within the word changes. Examples: man → men, woman → women, foot → feet, tooth → teeth, goose → geese, mouse → mice, louse → lice.
• Addition of -en or -ren: Examples: child → children, ox → oxen.
• No change: The singular and plural forms are the same. Examples: sheep → sheep, deer → deer, fish → fish, species → species, aircraft → aircraft.
• Foreign plurals: Some nouns retain their original plural forms from other languages, often Latin or Greek. Examples: analysis → analyses, basis → bases, crisis → crises, phenomenon → phenomena, criterion → criteria, curriculum → curricula (or curriculums), datum → data (though “data” is often used as a singular mass noun).

Categories of Irregular Nouns

Irregular nouns can be broadly classified into the following categories:

• Nouns with internal vowel changes: These nouns change a vowel within the word to form the plural.
• Nouns with -en or -ren plurals: These nouns add the suffix -en or -ren to form the plural.
• Nouns with no change in plural form: These nouns have the same form in both singular and plural.
• Nouns with foreign plurals: These nouns retain their original plural forms from other languages.

Examples of Irregular Nouns

The following tables provide examples of irregular nouns, categorized by the type of irregular plural formation.

Internal Vowel Change

This table highlights nouns that change their internal vowels to form plurals.

-f or -fe to -ves

These nouns change the final -f or -fe to -v and add -es.

-en or -ren Plurals

This table lists nouns that add -en or -ren to create their plural form.

No Change in Plural Form

This table showcases nouns that remain the same in both singular and plural forms.

Foreign Plurals

This table provides examples of nouns that retain their foreign plural forms.

-is to -es (from Greek)

Nouns ending in -is change it to -es. The plural ending is pronounced “-eez”: crises = CRY-seez.

Other common Latin plurals: cactus → cacti (or cactuses), fungus → fungi, nucleus → nuclei, stimulus → stimuli, larva → larvae, bacterium → bacteria.

Uncountable Nouns

Uncountable nouns (also known as mass nouns) are nouns that cannot be counted. They typically refer to substances, concepts, or abstract ideas. Because they cannot be counted, they generally do not have a plural form. Examples include: water, air, sand, information, advice, furniture, and happiness.

While uncountable nouns typically do not have plural forms, there are some exceptions. Sometimes, they can be used in a countable sense to refer to specific instances or types. For example:

• “Waters” can refer to bodies of water (e.g., “the waters of the lake”).
• “Sands” can refer to different types of sand (e.g., “the sands of the Sahara”).
• “Sugars” can refer to different types of sugar (e.g., “the sugars in fruit”).

It’s important to note that even when used in a countable sense, the meaning of the noun may be slightly different from its usual uncountable meaning.

Usage Rules for Regular and Irregular Nouns

Using regular and irregular nouns correctly involves understanding the rules for forming plurals and applying them appropriately. Here are some key usage rules to keep in mind:

• Always use the correct plural form: Pay close attention to whether a noun is regular or irregular and use the appropriate plural form. Avoid adding -s or -es to irregular nouns that have a different pluralization pattern (e.g., “childs” instead of “children”).
• Be aware of nouns with no change in plural form: Remember that some nouns have the same form in both singular and plural (e.g., “sheep,” “deer”). Avoid adding -s to these nouns in the plural.
• Use the correct verb agreement: The verb in a sentence must agree in number with the subject noun. If the subject is a plural noun, use a plural verb. If the subject is a singular noun, use a singular verb. For example: “The cats are sleeping” (plural noun, plural verb) vs. “The cat is sleeping” (singular noun, singular verb).
• Be careful with collective nouns: Words like team, family and committee name a group. American English usually treats them as singular (The team is winning). British English often uses a plural verb when it thinks of the members (The team are arguing among themselves). Both are correct in their own variety; be consistent within one text.
• Understand the usage of “data”: Data began as the plural of datum, and some scientific writing still uses it that way (the data are). In most everyday, business and journalistic writing it is treated as an uncountable noun with a singular verb (the data is clear), and major style guides accept both. Follow your teacher, journal or style guide.
• Consider the context: The correct plural form of a noun can sometimes depend on the context. For example, “fish” is the most common plural form of “fish,” but “fishes” can be used to refer to different species of fish.

Common Mistakes with Noun Plurals

Even experienced English speakers can make mistakes with noun plurals, especially when dealing with irregular nouns or less common words. Here are some common mistakes to watch out for:

Practice Exercises

Test your understanding of regular and irregular nouns with the following exercises. Fill in the blanks with the correct plural form of the noun in parentheses.

Exercise 1: Regular Nouns

Exercise 2: Irregular Nouns

Exercise 3: Mixed Regular and Irregular Nouns

Advanced Topics in Noun Pluralization

• Compound nouns: Compound nouns are nouns made up of two or more words. The pluralization of compound nouns can be tricky, as it depends on the structure of the noun. In general, the main word of the compound noun is pluralized. Examples: passer-by → passers-by, mother-in-law → mothers-in-law, toothbrush → toothbrushes. However, some compound nouns pluralize the last word. Examples: cupful → cupfuls, handful → handfuls.
• Nouns with multiple plural forms: Some nouns have more than one acceptable plural form, often with subtle differences in meaning or usage. Examples: index → indices or indexes, appendix → appendices or appendixes, formula → formulae or formulas.
• Numbers before a noun: When a number + noun works as an adjective before another noun, the noun stays singular, usually with a hyphen: a five-dollar bill, a ten-year-old boy, a three-week course. This is standard English, not an error. Without the following noun, use the plural: The boy is ten years old; It costs five dollars.
• The influence of regional dialects: Noun pluralization can vary depending on regional dialects. For example, some dialects may use different plural forms for certain nouns or have different rules for pluralizing compound nouns.

Frequently Asked Questions (FAQ)

1. What is the difference between a regular and an irregular noun?

   A regular noun forms its plural by adding -s or -es to the end of the singular form. An irregular noun does not follow this rule and has a unique plural form that must be memorized.

2. How do I know if a noun is regular or irregular?

   The best way to determine if a noun is regular or irregular is to consult a dictionary. Dictionaries typically provide the plural form of nouns, indicating whether they are regular or irregular. You can also learn common irregular nouns through practice and exposure to the English language.

3. Are there any rules for predicting the plural form of irregular nouns?

   While there are some patterns in the formation of irregular plurals (e.g., internal vowel changes, addition of -en), there are many exceptions to these patterns. It is generally best to memorize the plural forms of irregular nouns rather than relying on rules.

4. Is it acceptable to use the regular plural form for an irregular noun?

   In most cases, using the regular plural form for an irregular noun is considered incorrect. However, there are some exceptions. For example, “indexes” and “appendixes” are sometimes used as alternative plural forms for “indices” and “appendices,” respectively. It’s always best to consult a dictionary or style guide to determine the preferred plural form.

5. What should I do if I’m unsure of the plural form of a noun?

   If you are unsure of the plural form of a noun, consult a dictionary or online grammar resource. These resources will provide the correct plural form and any relevant usage notes.

6. Why do some nouns have the same form in both singular and plural?

   Mostly history. In Old English, some nouns (including the ancestors of sheep and deer) had a plural identical to the singular, and the pattern survived. Many words in this group are animals people hunt, fish or farm (deer, sheep, fish, salmon, trout, cod); others already end in -s (species, series) or are compounds like aircraft.

7. How do I pluralize compound nouns like “mother-in-law” or “passer-by”?

   Generally, you pluralize the main noun in the compound. So, “mother-in-law” becomes “mothers-in-law” and “passer-by” becomes “passers-by.” However, there are exceptions, so it’s best to check a dictionary if you’re unsure.

8. Is it ever correct to use “data” as a singular noun?

   Yes. Using data with a singular verb (the data shows) is standard in most modern writing and is accepted by major style guides. The plural use (the data show) is still common in scientific and academic writing. Both are correct; follow the style your reader expects.