leucine

/ˈluː.siːn/

//ˈluː.siːn// noun

"leucine" is a 7-letter English headword indexed on PlainSpell.

The verdict

“leucine” is uncommon English (frequency #57,517 among 2,297 “L” headwords), classed as a noun. The kind of spelling people second-guess.

#57,517
frequency rank, English
2,297
“L” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - An essential amino acid, C₆H₁₃NO₂, isomeric with isoleucine, found in most animal proteins; it is essential for growth in children.

Corpus desk

Index EN-leucine · leucine · English

leucine · rank #57,517 · 0 variants · 0 confusables

  • FREQ-RARE #57,517
  • LEN-LONG 7 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 2,297
  • PHOTO-FINISH lemongrass

Nearest frequency peer: lemongrass (-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.

Long-tail ranks near “leucine”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “leucine” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for leucine
PropertyValue
Headwordleucine
LanguageEnglish
Part of speechNoun
IPA/ˈluː.siːn/
Letters7
Frequency rank#57,517
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “leucine” in English

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

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

Ticks step logarithmically, so each one marks a roughly tenfold drop in how often the word turns up. Rare peers in the same band: “lemongrass” (#57,516), “lineal” (#57,519), “legalise” (#57,514). Among 2,297 “L” headwords, “leucine” is #57,517. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

leucine is uncommon English at frequency #57,517 among 2,297 “L” headwords, classed as anoun, transcribed /ˈluː.siːn/. Rarity is why readers land here mid-draft. Gloss: "An essential amino acid, C₆H₁₃NO₂, isomeric with isoleucine, found in most animal proteins; it is essential for growth in children.".

No misspelling variants are generated for leucine in our index, suggesting the orthography follows predictable English patterns. No close-neighbour confusable shows up for this headword in our dataset, suggesting its spelling stands apart enough that readers rarely confuse it with something else.

Etymologically, the entry records: Derived from Ancient Greek λευκός (leukós, “white”) + -ine, equivalent to leuco- + -ine. The correct English form is leucine, spelled L-E-U-C-I-N-E.

Definition

  1. 1
    An essential amino acid, C₆H₁₃NO₂, isomeric with isoleucine, found in most animal proteins; it is essential for growth in children.

Recorded use

Wiktionary example

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

  1. Thus, leucine is already being seen as a pharmaconutrient of great relevance for the supplementary feeding of malnourished and frail elderly and for specific subpopulations.

Etymology

Derived from Ancient Greek λευκός (leukós, “white”) + -ine, equivalent to leuco- + -ine.

Synonyms

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 "leucine"?
"leucine" is spelled L-E-U-C-I-N-E. The IPA pronunciation is /ˈluː.siːn/.
What does "leucine" mean?
As a noun, "leucine" means: An essential amino acid, C₆H₁₃NO₂, isomeric with isoleucine, found in most animal proteins; it is essential for growth in children.
How do you pronounce "leucine"?
The IPA (International Phonetic Alphabet) transcription for "leucine" is /ˈluː.siːn/. 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 "leucine"?
Derived from Ancient Greek λευκός (leukós, “white”) + -ine, equivalent to leuco- + -ine. 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 "leucine", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 7 letters (nearest by frequency rank).

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

Source: FrequencyWords open word-frequency list