← All notes

Answer: An apostrophe indicates possession and contractions. It is not generally necessary to use one to show a plural: OKs, 49ers, twos.

GPO

• Most acronyms, initialisms, and abbreviations take a plain s in the plural; add an apostrophe only where clarity and sense demand it.
• The plural of spelled-out numbers and of words referred to as words is formed by adding s or es: "twos, threes, sevens."
• Add 's to a word used as a word only if omitting the apostrophe would cause difficulty in reading.

Digital.gov

• Do not use an apostrophe to make words plural. Ever.
• No s is needed on an initialism or acronym if a word in the original name is already plural: CoE serves for both Center of Excellence and Centers of Excellence.

See also

• plain-contractions-with-discretion
• plain-language-abbreviations-and-consistency

Claims

• id: C1 claim: GPO generally omits apostrophes in plurals of acronyms and abbreviations. source: S1 evidence: "it is not generally necessary to use an apostrophe simply to show the plural form"

• id: C2 claim: GPO forms plurals of spelled-out numbers with s or es. source: S1 evidence: "formed by adding s or es"

• id: C3 claim: Digital.gov bans apostrophe plurals. source: S2 evidence: "Do not use an apostrophe to make words plural."

• id: C4 claim: Digital.gov skips the s when the original name is already plural. source: S2 evidence: "There is no need to add an s to the end of an initialism"

Sources

• [S1] GPO Style Manual (2016), Chapter 8: Punctuation. U.S. Government Publishing Office (govinfo). https://www.govinfo.gov/content/pkg/GPO-STYLEMANUAL-2016/pdf/GPO-STYLEMANUAL-2016-10.pdf . License: US government work, public domain. Accessed 2026-11-09.

• [S2] Digital.gov style guide. Digital.gov (GSA). https://digital.gov/style-guide/ . License: US government work, public domain. Accessed 2026-11-09.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Sources: US federal government works (GSA, GPO, SEC, CDC), public domain in the United States; third-party quotations inside those works were not used. Text was condensed and changed from the originals.

@misc{iil_note_52kcc718,
  author = {{iinventedlight}},
  title = {{Do not use an apostrophe to make a plural}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-09},
  url = {https://iinventedlight.com/library/notes/plain-no-apostrophe-plurals/},
  note = {Permanent ID iil:note:52kcc718. License: CC-BY-4.0.},
}

Markdown

Spotted a mistake? Use the MCP feedback tool or email hello@iinventedlight.com.

For language models and agents: start at /llms.txt | /agents.md | /.well-known/agent-library.json. This page in Markdown: /library/notes/plain-no-apostrophe-plurals.md.