cysteine

/ˈsɪs.təˌiːn/

//ˈsɪs.təˌiːn// noun

"cysteine" is a 8-letter English headword indexed on PlainSpell.

The verdict

“cysteine” has 12 generated spelling variants in the English index at frequency #43,590. The variants make it a useful spelling check.

#43,590
frequency rank, English
43,570
“C” headwords
12
tracked misspellings

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A sulphur-containing nonessential amino acid C₃H₇NO₂S found in most animal proteins; it readily oxidizes to cystine.

Corpus desk

Index EN-cysteine · cysteine · English

cysteine · rank #43,590 · 12 variants · 0 confusables

  • FREQ-MID #43,590
  • LEN-LONG 8 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-MID 12 variants
  • BOOK-DENSE 43,570
  • PHOTO-FINISH cushy

Nearest frequency peer: cushy (-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 neighbourhood for “cysteine”

Lower corpus rank = more everyday usage (inverted bar length for readability)

corpus weight

What this shows Bars show where “cysteine” sits against the nearest ranked English headwords in the FrequencyWords band, not a reprint of letter-browse containment.

Source FrequencyWords open word-frequency list As of May 6, 2026
Key facts for cysteine
PropertyValue
Headwordcysteine
LanguageEnglish
Part of speechNoun
IPA/ˈsɪs.təˌiːn/
Letters8
Frequency rank#43,590
Misspellings tracked12
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “cysteine” 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). cysteine lands here:

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

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

A misspelling magnet

The generator records 12 spelling variants around cysteine (IPA /ˈsɪs.təˌiːn/), anoun. Corpus frequency is #43,590 among 43,570 “C” headwords. Dominant gloss: "A sulphur-containing nonessential amino acid C₃H₇NO₂S found in most animal proteins; it readily oxidizes to cystine.".

Our generated misspelling index lists 12 likely wrong-spelling variants for cysteine, with forms such as "ccysteine", "csyteine", and "cysetine". 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. No confusable counterpart is on file for this word, a sign it's visually distinctive enough not to be mixed up with another word.

Etymologically, the entry records: An alteration of cystine, see -eine. The correct English form is cysteine, spelled C-Y-S-T-E-I-N-E.

Definition

  1. 1
    A sulphur-containing nonessential amino acid C₃H₇NO₂S found in most animal proteins; it readily oxidizes to cystine.

Etymology

An alteration of cystine, see -eine.

Synonyms

E910 when used as a food additiveE920 when used as an improving agentCys when viewed as a monomer in proteins

This word in other languages

Common misspellings

Also misspelled as:

  • ccysteine
  • csyteine
  • cysetine
  • cyssteine
  • cysteien
  • cysteinne
  • cystenie
  • cystiene
  • cystteine
  • cytseine
  • cyysteine
  • ycsteine

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of cysteine - measured in single-character edits (insert, delete, or substitute a letter). Larger bars are easier to catch; one-edit slips are the sneakiest.

ccysteine1csyteine2cysetine2cyssteine1cysteien2cysteinne1cystenie2cystiene2
Edit distance from "cysteine"

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.

PlainSpell is rendered directly from structured Wiktionary extracts and open word-frequency lists, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 6, 2026. Primary sources: Wiktionary (via kaikki.org) and FrequencyWords.

Frequently Asked Questions

How do you spell "cysteine"?
"cysteine" is spelled C-Y-S-T-E-I-N-E. The IPA pronunciation is /ˈsɪs.təˌiːn/.
What does "cysteine" mean?
As a noun, "cysteine" means: A sulphur-containing nonessential amino acid C₃H₇NO₂S found in most animal proteins; it readily oxidizes to cystine.
What are common misspellings of "cysteine"?
Common misspellings include "ccysteine", "csyteine", "cysetine", "cyssteine", "cysteien". The correct spelling is "cysteine".
How do you pronounce "cysteine"?
The IPA (International Phonetic Alphabet) transcription for "cysteine" is /ˈsɪs.təˌiːn/. 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 "cysteine"?
An alteration of cystine, see -eine. 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 "cysteine", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 8 letters (nearest by frequency rank).

Similar misspelling depth

Headwords with a similar count of attested misspellings (12 here; floor ≥5).

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