en mass (en masse)

Short version: write en masse (two words, no hyphen). It means "all together," "collectively," or "as a group."

Below: concise rules, origin, spacing/hyphenation and grammar notes, many real examples for work/school/casual use, wrong→right fixes, and ready-to-copy rewrites.

Quick answer

Write en masse (two words, no hyphen). Do not write en mass, en-mass, or enmass. It usually functions adverbially-modifying a verb to mean "collectively" or "all at once."

Correct: en masse - two words, lowercase unless at sentence start.
Incorrect: en mass, en-mass, enmass.
Typical placement: after the verb or verb phrase it modifies (The team left en masse).

Core explanation: origin and one-line rule

En masse comes from French and keeps the two-word form in English. It describes many people or things acting together-equivalent to "collectively" or "all at once."

Editing rule: when you see en mass or en-mass, replace it with en masse and check that it follows the verb or verb phrase.

Meaning: all together, collectively.
Form: two words, no hyphen.
Function: adverbial phrase (modifies verbs/clauses).
Example: Correct: The staff resigned en masse. -
Incorrect: The staff resigned en mass.

Spacing and hyphenation (explicit rules)

Keep the two words separate. Do not hyphenate or combine them-dictionaries list en masse as two words.

When searching a document, check for variants: en mass, en-mass, enmass.

Correct: en masse
Incorrect: en mass, en-mass, enmass
Search tip: run a search for both "en mass" and "en-mass" to catch common errors.

Wrong: We cancelled the event en-mass.
Right: We cancelled the event en masse.
Wrong: Applications were submitted enmass yesterday.
Right: Applications were submitted en masse yesterday.

Grammar: placement, agreement, and punctuation

En masse usually follows the verb (subject + verb + en masse). It does not agree with the subject-because it modifies the action, not the noun.

Only add commas when required by sentence structure. Don't add commas simply because the phrase is foreign.

Placement: most commonly after the verb (They left en masse).
No agreement: en masse stays the same for singular or plural subjects.
Commas: use only if the syntax calls for them.

Wrong: En masse, the board agreed to the terms.
Right: The board agreed to the terms en masse.
Wrong: The crowd left, en mass, when the storm hit.
Right: The crowd left en masse when the storm hit.

Real usage and tone: work, school, and casual examples

En masse fits neutral-to-formal contexts such as reports, news, or academic prose. In casual speech, "all at once" or "together" often sounds more natural.

Below are realistic sentences you can copy or adapt.

Work

The engineering team deployed the update en masse overnight to minimize downtime.
After the announcement, employees requested meetings en masse.
Proposals were rejected en masse during the review session.

School

Students checked out the books en masse at the start of term.
The department admitted transfers en masse to balance class sizes.
Lab submissions arrived en masse just before the deadline.

Casual

Fans flooded the streets en masse after the team won.
Everyone left the café en masse when it started raining.
People bought the limited edition en masse, so stores sold out fast.

Examples: common wrong → right sentence pairs (copyable fixes)

Use these pairs as templates. Replace subjects or verbs as needed while keeping the corrected placement.

Editors commonly encounter misspelling, hyphenation, and leading-the-sentence placement errors.

Wrong: The volunteers signed up en mass for the cleanup. -
Right: The volunteers signed up en masse for the cleanup.
Wrong: Protesters moved en-mass toward City Hall. -
Right: Protesters moved en masse toward City Hall.
Wrong: Students submitted their essays en mass before midnight. -
Right: Students submitted their essays en masse before midnight.
Wrong: Employees filed grievances en mass after the policy change. -
Right: Employees filed grievances en masse after the policy change.
Wrong: Customers queued en-mass for the product release. -
Right: Customers queued en masse for the product release.
Wrong: Attendees walked out en mass when the speaker didn't show. -
Right: Attendees walked out en masse when the speaker didn't show.
Wrong: We removed the files en mass from the server. -
Right: We removed the files en masse from the server.

Try your own sentence

Test the whole sentence, not just the phrase. Context usually shows whether en masse fits or whether a plain alternative would be clearer.

Rewrite help: ready-to-use swaps (formal → plain)

Choose en masse for neutral or formal tone; pick a plain alternative for conversational clarity. Each block shows the wrong sentence and two polished options.

Wrong: The interns were hired en mass.
Formal: The interns were hired en masse. Plain: The interns were hired all at once.
Wrong: Voters turned out en mass for the election.
Formal: Voters turned out en masse for the election. Plain: Voters showed up in large numbers / all at once for the election.
Wrong: We patched the systems en mass overnight.
Formal: We patched the systems en masse overnight. Plain: We patched all the systems at once overnight.
Wrong: The cast left en mass after rehearsal.
Formal: The cast left en masse after rehearsal. Plain: The cast all left together after rehearsal.
Wrong: Requests were denied en mass by the committee.
Formal: Requests were denied en masse by the committee. Plain: The committee denied the requests all at once.
Wrong: Customers returned the items en mass.
Formal: Customers returned the items en masse. Plain: Customers returned the items together/in large numbers.

Memory trick and quick editing checklist

Mnemonic: "en + masse" = 'in' (en) + 'mass' (group). Picture a mass of people moving together-two words for two parts.

Checklist: 1) Search for en mass / en-mass; 2) Replace with en masse or a plain alternative; 3) Ensure placement after the verb; 4) Read the sentence aloud for tone.
Quick test: substitute "together"-if the sentence still works, en masse is appropriate.

Similar mistakes and related French phrases to watch

Writers who slip on en masse sometimes mishandle other French loans. Watch for spacing, accents, and hyphenation in phrases like résumé, à la carte, en route, and au contraire.

When a borrowed phrase obscures meaning, prefer a clear English equivalent.

Correct forms: résumé, à la carte, en route, au contraire, en masse.
Common incorrect variants: alacarte, enroute, au-contraire.
Wrong: She submitted her resume en mass for the openings. -
Right: She submitted her résumé en masse for the openings.
Wrong: Orders were processed enroute to the fulfillment center. -
Right: Orders were processed en route to the fulfillment center.

Fix your own sentence: a short editing routine

Three-step routine: 1) Search the document for 'en mass' and 'en-mass'; 2) Replace with 'en masse' or a plain-English substitute; 3) Read the sentence aloud to check tone and flow.

Before: Customers emailed complaints en mass during the outage.
After: Customers emailed complaints en masse during the outage.
Before: The players walked off the field en mass after the brawl.
After (plain): The players walked off the field all at once after the brawl.

FAQ

Is it en masse or en mass?

Correct: en masse (two words). 'En mass', 'en-mass', and 'enmass' are incorrect.

Can I hyphenate en masse?

No. Standard English keeps it as two words without a hyphen.

When should I use en masse vs a plain alternative?

Use en masse in neutral or formal writing. For casual speech or when clarity matters, use 'all at once', 'together', or 'collectively'.

Does en masse change with singular/plural subjects?

No. En masse is adverbial and does not change with subject number.

How do I check my writing quickly for this mistake?

Search your document for 'en mass' and 'en-mass'. Replace with 'en masse' or a plain-English alternative, then read the sentence aloud to confirm tone and flow.

Quick fix: run a short check before you publish

Run a one-minute search for 'en mass' and 'en-mass' and replace accordingly. Add this quick check to your final proofing routine: search variants → choose en masse or a plain alternative → read aloud. The habit prevents the error.