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Pluralizer & Singularizer

Convert English nouns between singular and plural forms using simple suffix rules plus a short list of irregular words.

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About this tool

The Pluralizer & Singularizer converts English nouns between their singular and plural forms. It applies the common suffix rules — add -es after s, x, z, ch or sh, change a consonant + y to -ies, change a final f or fe to -ves, otherwise add -s — and reverses them when singularizing. A built-in list of 25 irregular and invariant nouns covers man/men, woman/women, child/children, person/people, tooth/teeth, foot/feet, mouse/mice, goose/geese, ox/oxen, knife/knives, leaf/leaves and similar, plus sheep, deer, fish, moose, series and species, which stay the same. Words outside that list follow the rules, so Latin and Greek plurals (datum, criterion) and exceptions like roof or potato come out wrong. Enter one word per line for bulk processing; every word on a line is converted. It is handy for quick checks when naming tables, API resources or UI labels.

Why use it

  • Handles common English irregular plurals such as child/children, person/people and mouse/mice.

  • Supports bulk conversion — process many words at once.

  • Useful for developers naming API resources, database tables, or UI labels.

  • Runs entirely in the browser with no external dictionary API needed.

  • Applies the standard -s, -es, -ies and -ves rules consistently in both directions.

  • Helps maintain consistent naming conventions across REST APIs and database schemas.

How to use

  1. Choose a mode: Singularize → Pluralize or Pluralize → Singularize.
  2. Enter one or more English nouns in the Input box, one per line for bulk.
  3. Click Convert to fill the Output box; after that it updates as you type.
  4. Inspect the converted output line by line to spot any words you want to override manually.
  5. Click Copy to copy all converted words to your clipboard.

When it helps

  • Generating plural or singular noun forms for REST API endpoint naming.
  • Proofreading copy where plural forms need to be checked quickly.
  • Building word lists for NLP datasets or game dictionaries.
  • Naming database tables consistently (e.g. all plural or all singular).
  • Generating GraphQL types or Prisma models that follow plural-table conventions.
  • Localizing UI labels that need both singular and plural forms (e.g. '1 item' vs '5 items').

Examples

Regular and irregular

Input

cat mouse child

Expected result

cats mice children

Rule-based endings

Input

box city wolf

Expected result

boxes cities wolves

Singularizing

Input

feet teeth geese

Expected result

foot tooth goose

Tips

  • Avoid feeding the tool verbs or adjectives — only nouns produce reliable singular/plural pairs.
  • For database schema design, pick one convention (all plural or all singular) and stick with it project-wide.
  • Latin and Greek loanwords such as datum, criterion and phenomenon are not in the irregular list; write their plurals by hand.
  • For CMS content, use plural form for collection names ('articles', 'products') and singular for item identifiers.
  • Singularizing words that end in -ves, -ies or a double s can go wrong (gloves → glof, glass → glas), so review those lines.

Frequently Asked Questions

Does it handle irregular plurals like 'data' or 'criteria'?
No. The irregular list has 25 everyday nouns (child, person, mouse, foot, knife and so on). Latin and Greek loanwords follow the regular rules, so datum becomes datums, criterion becomes criterions, and data stays data when singularized.
What if the word has no standard plural (e.g. 'sheep', 'fish')?
Sheep, deer, fish, moose, series and species are in the built-in list and returned unchanged. Other uncountable nouns, such as water or music, simply get an -s.
Can I process multiple words at once?
Yes. Enter one word per line and all will be converted in a single operation.
Does it work for compound nouns like 'mother-in-law'?
No. The rules look only at the end of the word, so mother-in-law becomes mother-in-laws. Fix hyphenated compounds by hand.
Is this only for English?
Yes. The tool is built specifically for English morphological rules.
Does it preserve original capitalization?
Only the first letter. A capitalized irregular word keeps its capital (Child → Children), but all-caps input is not matched: CAT becomes CATs and CHILD becomes Children.
Which words come out wrong?
Anything that breaks the suffix rules and is not in the 25-word list: roof → rooves, potato → potatos, and when singularizing, gloves → glof, movies → movy, glass → glas and status → statu. Check the output before using it.
What happens if I paste a sentence?
Every word on the line is converted, not just the nouns, so 'the red car' becomes 'thes reds cars'. Enter nouns only, one per line.

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Glossary

Plural
The grammatical form indicating more than one of something (e.g. cats, mice, children).
Singular
The grammatical form indicating exactly one of something (e.g. cat, mouse, child).
Irregular plural
A plural that does not follow standard English rules — typically formed by vowel change or kept from another language.
Mass noun
A noun that does not take a plural form because it refers to an uncountable substance (e.g. water, music).
Invariant noun
A noun whose singular and plural forms are identical (e.g. sheep, deer, fish).
Inflection
The change in word form (suffix, vowel change) that conveys grammatical information like number or tense.
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