# protein

> English word · Noun · IPA /ˈpɹəʊ.ti.ɪn/ · frequency rank #2,851

## Definitions
1. Any of numerous large, complex naturally-produced molecules composed of one or more long chains of amino acids, in which the amino acid groups are held together by peptide bonds.
2. One of three major classes of food or source of food energy (4 kcal/gram) abundant in animal-derived foods (meat) and some vegetables, such as legumes.
3. A food rich in protein, often a meat or meat substitute.

## Etymology
From proto- + -ein. Suggested by Jöns Jacob Berzelius in a letter to Gerardus Johannes Mulder, from French protéine and German Protein, both coined based on Ancient Greek πρωτεῖος (prōteîos, “primary”), from πρῶτος (prôtos, “first”).

## Easily confused with
- **proven** (https://plainspell.com/en/vs/protein-vs-proven)
- **proton** (https://plainspell.com/en/vs/protein-vs-proton)
- **protest** (https://plainspell.com/en/vs/protein-vs-protest)
- **Proteus** (https://plainspell.com/en/vs/protein-vs-proteus)
- **protect** (https://plainspell.com/en/vs/protect-vs-protein)
- **protégé** (https://plainspell.com/en/vs/protege-vs-protein)

## Common misspellings (10)
`portein`, `pprotein`, `proetin`, `proteinn`, `proteni`, `protien`, `prottein`, `prrotein`, `prtoein`, `rpotein`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/protein