Plural Words in English: Understanding the Differences

Many learners believe English plurals are simple, just add -s. In reality, English plural words follow
different systems depending on history, origin, and usage. Some plurals come from Old English,
others from Latin or Greek, and some nouns never change at all.

Understanding these differences helps you avoid mistakes, sound natural, and
remember forms more easily.

1. Classic Irregular Plurals (Old English Origin)

These plurals come from Old English vowel mutation (umlaut).
They are fixed forms and must be memorized.

Common Examples

• ox → oxen
• goose → geese
• mouse → mice
• child → children

In Sentences

• One ox is working in the field → Two oxen are working.
• The child is sleeping → The children are sleeping.
• A mouse ran away → Two mice ran away.

❌ Incorrect forms (never use):
childs, mouses, gooses

➡️ These forms cannot be regularized.

2. Same Form in Singular and Plural (Invariant Nouns)

Some English nouns do not change at all between singular and plural.

Examples

• deer → deer
• moose → moose

In Sentences

• I saw one moose yesterday.
• We saw three moose in the forest.
• A deer is grazing → Several deer are grazing.

➡️ These nouns are mostly animals, often used in
collective or hunting contexts.

3. Latin-Origin Plurals (Scientific / Academic English)

Some English words come from Latin and keep Latin plural forms, especially in
formal or academic contexts.

Examples

• cactus → cacti
• fungus → fungi

Modern Accepted Alternatives

• cactuses
• funguses

Usage by Context

• Scientific / academic: cacti, fungi
• Business / everyday English: cactuses, funguses

➡️ Both are correct. Register matters more than grammar here.

4. The Tricky One: Octopus

This is one of the most misunderstood plural words in English.

Correct Plural Forms

1. octopuses ✅ (BEST and safest choice)
2. octopi ⚠️ (common but historically incorrect)
3. octopodes ⚠️ (technically correct, very rare)

Why?

• Octopus comes from Greek, not Latin.
• Greek plural: octopodes
• Octopi wrongly applies a Latin rule.
• Octopuses follows standard English pluralization →
  modern standard usage.

➡️ Best choice in real life:
✔️ octopuses

5. Summary Table

Practical Rule (Very Important)

When multiple plural forms exist:

• ✅ Everyday / business English → use -s
• ✅ Scientific / academic English → Latin or Greek plural may be preferred
• ❌ Never invent a plural that “sounds right”

Read also: English prepositions on, in, at, of, for, from, to, into, by, across, around, near, with, about, along…

Exercises on Plural Words in English

Exercise 1 – Choose the Correct Plural

Choose the correct plural form.

1. One ox, two ______
   a) oxes
   b) oxen
2. One goose, three ______
   a) gooses
   b) geese
3. One cactus, many ______ (scientific context)
   a) cactuses
   b) cacti
4. One deer, five ______
   a) deers
   b) deer
5. One octopus, several ______ (modern standard English)
   a) octopi
   b) octopuses

Exercise 2 – Fill in the Blank

Fill in the blank with the correct plural form.

1. The farmer owns three ______ (ox).
2. We saw many ______ in the forest (moose).
3. Two ______ were playing in the yard (child).
4. The lab studies different ______ growing on bread (fungus).
5. At the aquarium, we watched several ______ moving slowly (octopus).

Exercise 3 – Correct the Mistake

Each sentence contains an error. Rewrite it correctly.

1. The childs are playing outside.
2. I saw two mouses in the kitchen.
3. Several deers were crossing the road.
4. The scientist collected rare funguses in the lab.
5. Three octopi escaped from the tank.

Exercise 4 – Choose the Best Option (Context Matters)

Choose the best plural based on context.

1. Academic paper:
   “Different ______ were observed under the microscope.”
   a) funguses
   b) fungi
2. Business email:
   “We sell decorative ______ for offices.”
   a) cacti
   b) cactuses
3. Everyday conversation:
   “Look! Those ______ are swimming together.”
   a) octopi
   b) octopuses

✅ ANSWERS — ENGLISH

Exercise 1

1. oxen
2. geese
3. cacti
4. deer
5. octopuses

Exercise 2

1. oxen
2. moose
3. children
4. fungi
5. octopuses

Exercise 3 (Corrected)

1. The children are playing outside.
2. I saw two mice in the kitchen.
3. Several deer were crossing the road.
4. The scientist collected rare fungi in the lab.
5. Three octopuses escaped from the tank.

Exercise 4

1. fungi
2. cactuses
3. octopuses

Sources: PinterPandai, EF, Woodward Education
Photo credit: GPT

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