millimètrevsmmTell them apart

Quick tell: millimètre is a noun, mm is a symbol, so they fill different roles in a sentence.

Which to use

“millimètre” is a noun and “mm” is a symbol - they look or sound alike but fill different roles in a sentence.

#26,438
“millimètre” frequency rank
#1,092
“mm” frequency rank
27530
confusion score

Side-by-Side Comparison

Feature millimètre mm
Definition Unité de mesure de longueur du Système international (SI), valant 10⁻³ mètre, et dont le symbole est mm. Symbole du millimètre, unité de mesure de longueur du Système international (SI), valant 0,001 mètre (10⁻³ mètre).

Same sound, different letters: millimètre vs mm

Muted letters are shared; highlighted letters are the only spelling cue when pronunciation matches. Shared run: 2 letters.

10 ch
millimètre
2 ch
mm

Same sound, different spelling - millimètre / mm

Say them out loud and nothing separates them: millimètre and mm carry the same recorded pronunciation, \mi.li.mɛtʁ\. Grammar is what tells them apart: one is anoun, the other asymbol, so most sentences will only accept one of them. They differ by 8 letter(s) in length. Our composite confusion score for this pair is 27530, derived from the frequency rank of both members and their visual similarity.

millimètre is recorded at frequency rank #26,438, classified as anoun, pronounced \mi.li.mɛtʁ\. mm is at rank #1,092, tagged as asymbol, pronounced \mi.li.mɛtʁ\.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 27530, this pair ranks #328,377 of 440,172 scored French confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of millimètre vs mm

Shared letters: m. Private to "millimètre": eilrtè. Private to "mm": -.

"millimètre" · 10 letters · shape CVCCVCVCCV  ·  "mm" · 2 letters · shape CC

Frequently Asked Questions

Is swapping "millimètre" for "mm" ever safe?
No - they are not even the same part of speech. "millimètre" is a noun and "mm" a symbol, so a sentence built for one is usually ungrammatical with the other.
Frequency check: "millimètre" vs "mm" - which ranks higher?
"mm" is the more common of the two: it sits at frequency rank #1,092 in our French list, against #26,438 for "millimètre". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

After this comparison

Sound matches; spelling doesn't. Use the exits below to lock the right form or check a cousin pair.

  • Full dictionary entry for "millimètre" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "mm" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #328,377 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
  • "millimètre" and "mm" also get mixed up with nearby pairs, the highest-scored neighbour is "mm vs MWh". Nearby pair

Confusion rank #328,377 of 440,172 scored French pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list