lumen

/ˈluːmən/

//ˈluːmən// noun

By · According to Wiktionary data (CC BY-SA) ·

"lumen" is a 5-letter English headword indexed on PlainSpell.

The verdict

“lumen” is a moderately-common English word, ranked #25,829 in English word frequency and used as a noun.

#25,829
frequency rank, English
5
letters
7
tracked misspellings
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - In the International System of Units, the derived unit of luminous flux; the light that is emitted in a solid angle of one steradian from a source of one candela. Symbol: lm.

Visual similarity to commonly confused words

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

lumen vs lun
60% similar
lumen vs lump
60% similar
lumen vs lure
60% similar

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

Key facts for lumen
PropertyValue
Headwordlumen
LanguageEnglish
Part of speechNoun
IPA/ˈluːmən/
Letters5
Frequency rank#25,829
Misspellings tracked7
Confusable pairs20
SourceWiktionary (kaikki.org)

Where “lumen” sits in English frequency

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

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

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Spelling & Dictionary Insight

The English entry for lumen is 5 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /ˈluːmən/. Corpus data places it at rank #25,829 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 4 distinct senses for this headword, so context determines which meaning a reader should apply.

Our generated misspelling index lists 7 likely wrong-spelling variants for lumen, with forms such as "llumen", "lmuen", and "luemn". Every one of these variants traces to a single-character edit -- an added or dropped letter, a swapped consonant, or a vowel swap -- the kind of slip a spell-checker is built to catch. It also participates in 20 confusable-pair relationships, "lun", "lump", "lure", 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 lūmen (“light, an opening”). Use as a unit was first adopted by French physicist André Blondel in 1894. The correct English form is lumen, spelled L-U-M-E-N.

Definition

  1. 1
    In the International System of Units, the derived unit of luminous flux; the light that is emitted in a solid angle of one steradian from a source of one candela. Symbol: lm.
  2. 2
    The cavity or channel within a tube or tubular organ.
  3. 3
    The cavity bounded by a plant cell wall.
  4. 4
    The bore of a tube such as a hollow needle or catheter.

Etymology

Borrowed from Latin lūmen (“light, an opening”). Use as a unit was first adopted by French physicist André Blondel in 1894.

This word in other languages

lumen(Français)Lumen(Deutsch)lúmen(Português)

Common misspellings

Also misspelled as: llumen,lmuen,luemn,lumenn,lummen,lumne,ulmen

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of lumen - counted as single-character edits (an insertion, a deletion, or a substituted letter). The larger the bar, the easier the typo is to spot; one-edit slips are the ones that sneak past readers.

llumen1lmuen2luemn2lumenn1lummen1lumne2ulmen2
Edit distance from "lumen"

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 "lumen"?
"lumen" is spelled L-U-M-E-N. The IPA pronunciation is /ˈluːmən/.
What does "lumen" mean?
As a noun, "lumen" means: In the International System of Units, the derived unit of luminous flux; the light that is emitted in a solid angle of one steradian from a source of one candela. Symbol: lm.
What words are commonly confused with "lumen"?
"lumen" is commonly confused with "lun", "lump", "lure". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "lumen"?
The IPA (International Phonetic Alphabet) transcription for "lumen" is /ˈluːmən/. 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 "lumen"?
Borrowed from Latin lūmen (“light, an opening”). Use as a unit was first adopted by French physicist André Blondel in 1894. 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.

Using “lumen”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is L-U-M-E-N - every other letter order is a misspelling in standard orthography.
  • Say it as /ˈluːmən/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Don't mix it up with “lun” - see the side-by-side comparison. lumen vs lun
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

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

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list