LuvsluxTell them apart

Quick tell: Lu is a name, lux is a noun, so they fill different roles in a sentence.

Which to use

“Lu” is a name and “lux” is a noun - they look or sound alike but fill different roles in a sentence.

#1,333
“Lu” frequency rank
#18,246
“lux” frequency rank
19579
confusion score

Side-by-Side Comparison

Feature Lu lux
Definition Commune de la province d’Alexandrie dans le Piémont en Italie. Unité de mesure d’éclairement lumineux du Système international, définie comme lumen par mètre carré, dont le symbole est lx.

Where the eye mixes Lu and lux

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.

2 ch
Lu
3 ch
lux

Look-alike desk: Lu vs lux

These two trip readers on the page rather than in the ear: Lu is \ly\ while lux is \lyks\. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 extra letter(s) - “Lu” sits inside “lux”, and the parts of speech differ too (name vs noun), which is usually the fastest check. Our composite confusion score for this pair is 19579, derived from the frequency rank of both members and their visual similarity.

Lu is recorded at frequency rank #1,333, classified as aname, pronounced \ly\. lux is at rank #18,246, tagged as anoun, pronounced \lyks\.

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 19579, this pair ranks #372,566 of 440,172 scored French confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of Lu vs lux

Shared letters: lu. Private to "Lu": -. Private to "lux": x.

"Lu" · 2 letters · shape CV  ·  "lux" · 3 letters · shape CVC

Frequently Asked Questions

Is swapping "Lu" for "lux" ever safe?
No - they are not even the same part of speech. "Lu" is a name and "lux" a noun, so a sentence built for one is usually ungrammatical with the other.
Frequency check: "Lu" vs "lux" - which ranks higher?
"Lu" is the more common of the two: it sits at frequency rank #1,333 in our French list, against #18,246 for "lux". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

After this comparison

Eye-level mix-up between "Lu" and "lux" is sorted above. Next: full entries or other pairs that share a letter shape.

  • Full dictionary entry for "Lu" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "lux" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #372,566 of 440,172 scored French confusable pairs in this corpus vintage. Corpus statistics
  • "Lu" and "lux" also get mixed up with nearby pairs, the highest-scored neighbour is "lep vs lux". Nearby pair

Confusion rank #372,566 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