lux

/lʌks/

//lʌks// noun

"lux" is a 3-letter English headword indexed on PlainSpell.

The verdict

“lux” sits in 20 confusable pairs (corpus #18,878) as a noun. The look-alike neighbours are the real trap.

#18,878
frequency rank, English
2,297
“L” headwords
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - In the International System of Units, the derived unit of illuminance or illumination; one lumen per square metre. Symbol: lx

Corpus desk

Index EN-lux · lux · English

lux · rank #18,878 · 0 variants · 20 confusables

  • FREQ-MID #18,878
  • LEN-MID 3 letters
  • VOW-1 1 vowel
  • CONFUS-HIGH 20 pairs
  • VAR-0 0 variants
  • BOOK-MID 2,297
  • PHOTO-FINISH lunchtime

Nearest frequency peer: lunchtime (-1 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Frequency neighbours of confusable “lux”

Peers at similar corpus weight, separate from look-alike pairs below

corpus weight

What this shows Bars place “lux” against nearest ranked English headwords, not a reprint of the confusable-pair desk.

Source FrequencyWords open word-frequency list As of September 3, 2026

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

lux vs LV
0% similar
lux vs lx
67% similar
lux vs LZ
0% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for lux
PropertyValue
Headwordlux
LanguageEnglish
Part of speechNoun
IPA/lʌks/
Letters3
Frequency rank#18,878
Misspellings tracked0
Confusable pairs20
SourceWiktionary (kaikki.org)

Corpus rank beside confusables of “lux”

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right).luxlands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Same rarity band neighbours include “lunchtime” (#18,877), “mace” (#18,879), “lulu” (#18,876). Among 2,297 “L” headwords, “lux” is #18,878. Source: FrequencyWords open word-frequency list.

Easy to mix with look-alikes

The spelling risk for lux is neighbouring look-alikes ("LV", "lx", …), not just typos; it is anoun pronounced /lʌks/. Frequency #18,878 among 2,297 “L” headwords. Gloss: "In the International System of Units, the derived unit of illuminance or illumination; one lumen per square metre. Symbol: lx".

The misspelling generator found no plausible variants for lux, a sign its spelling follows regular English conventions. It also participates in 20 confusable-pair relationships, "LV", "lx", "LZ", and more, since the words sound or look close enough that writers reach for the wrong one mid-sentence.

Etymologically, the entry records: Borrowed from Latin lūx (“light”), from Proto-Indo-European *lewk- (“white; light; bright”). Cognates include Ancient Greek λευκός (leukós, “white, blank, light, bright, clear”), Ancient Greek λύκη (lúkē, “light, morning twilight”), Sanskrit रोचते (rocate),… The correct English form is lux, spelled L-U-X.

Definition

  1. 1
    In the International System of Units, the derived unit of illuminance or illumination; one lumen per square metre. Symbol: lx

Recorded use

Wiktionary examples

These source excerpts show how lux appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. Some volunteers slept in ambient light of about 100 lux and some in only 3 lux, which is close to total darkness.
  2. For quotations using this term, see Citations:lux.

Etymology

Borrowed from Latin lūx (“light”), from Proto-Indo-European *lewk- (“white; light; bright”). Cognates include Ancient Greek λευκός (leukós, “white, blank, light, bright, clear”), Ancient Greek λύκη (lúkē, “light, morning twilight”), Sanskrit रोचते (rocate), Middle Persian 𐭩𐭥𐭬 (rōz, “day”) and Old English lēoht (noun) (English light).

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "lux"?
"lux" is spelled L-U-X. The IPA pronunciation is /lʌks/.
What does "lux" mean?
As a noun, "lux" means: In the International System of Units, the derived unit of illuminance or illumination; one lumen per square metre. Symbol: lx
What words are commonly confused with "lux"?
"lux" is commonly confused with "LV", "lx", "LZ". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "lux"?
The IPA (International Phonetic Alphabet) transcription for "lux" is /lʌks/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "lux"?
Borrowed from Latin lūx (“light”), from Proto-Indo-European *lewk- (“white; light; bright”). Cognates include Ancient Greek λευκός (leukós, “white, blank, light, bright, clear”), Ancient Greek λύκη (lúkē, “light, morning twilight”), Sanskrit रोचते... See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "lux", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 3 letters (nearest by frequency rank).

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

Source: FrequencyWords open word-frequency list