Standard Lemma guide

cysteine

noun · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • Received-Pronunciation: /ˈsɪs.təˌiːn/
  • Received-Pronunciation: /ˈsɪs.tə.ɪn/
  • Received-Pronunciation: /ˈsɪs.tiˌiːn/
  • Received-Pronunciation: /ˈsɪs.ti.ɪn/
  • General-American: /ˈsɪs.təˌin/
  • General-American: /ˈsɪs.tə.ɪn/
  • General-American: /ˈsɪs.tiˌin/
  • General-American: /ˈsɪs.ti.ɪn/
  • General-American: /ˈsɪˌstin/
  • Southern-England: Recorded audio is listed in the source snapshot.
  • rhymes with -ɪstin

1

noun

Meaning 1

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

Definition source: English Wiktionary via Wiktextract

Usage: countable, uncountable

Topics: biochemistry, biology, chemistry, microbiology, natural-sciences, physical-sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

an amino acid containing sulfur that is found in most proteins; oxidizes on exposure to air to form cystine

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

Broader terms: amino acid, aminoalkanoic acid

History

Etymology

An alteration of cystine, see -eine.

Across languages

Translations

24 source translations are retained for this English entry.

  • Bulgarian: цистеин (cistein) — nonessential amino acid
  • Catalan: cisteïna — nonessential amino acid
  • Chinese Mandarin: 半胱氨酸 (bànguāng'ānsuān) — nonessential amino acid
  • Czech: cystein — nonessential amino acid
  • Danish: cystein — nonessential amino acid
  • Esperanto: cisteino — nonessential amino acid
  • Finnish: kysteiini — nonessential amino acid
  • French: cystéine — nonessential amino acid
  • Galician: cisteína — nonessential amino acid
  • German: Cystein — nonessential amino acid
  • Greek: κυστεΐνη (kysteḯni) — nonessential amino acid
  • Hungarian: cisztein — nonessential amino acid
  • Italian: cisteina — nonessential amino acid
  • Japanese: システイン (shisutein) — nonessential amino acid
  • Kazakh: цистеин (sistein) — nonessential amino acid
  • Kyrgyz: цистеин (tsistein) — nonessential amino acid
  • Mongolian: цистейн (cistejn) — nonessential amino acid
  • Persian: سیستئین (siste'in) — nonessential amino acid
  • Polish: cysteina — nonessential amino acid
  • Portuguese: cisteína — nonessential amino acid
  • Romanian: cisteină — nonessential amino acid
  • Russian: цистеи́н (cisteín) — nonessential amino acid
  • Spanish: cisteína — nonessential amino acid
  • Swedish: cystein — nonessential amino acid
Real reading context

cysteine in complete knowledge articles