# protein

/ˈpɹoʊˌtin/ (US) · /pɹˈəʊtiːn/ (UK)

Source: https://englishreference.com/word/protein
Updated: 2026-06-19

## Senses

### 1. biological molecule

noun · CEFR B2 · Technical

a complex natural molecule made of amino acids that builds and repairs your body.

For teachers: any of a class of nitrogenous organic compounds which have large molecules composed of one or more long chains of amino acids.

- The scientist studied how the protein changes shape when it gets hot.
- The researchers identified a specific protein responsible for transporting calcium across the cell membrane, which could lead to new treatments for bone diseases.

Usage: Often used as a countable noun in scientific contexts when referring to specific types.

### 2. nutritional category

noun · CEFR B2

one of the main parts of food that gives you energy and helps muscles grow.

For teachers: one of the three primary macronutrients, essential for the growth and repair of body tissues.

- Athletes often eat a lot of protein to help their muscles recover after exercise.
- Nutritionists recommend balancing your intake of protein, carbohydrates, and fats to maintain a healthy metabolic rate.

Usage: Usually uncountable when referring to the nutrient in general.

### 3. a type of food

noun · CEFR B2

a food that is high in protein, such as meat, fish, or tofu.

For teachers: a specific food item or ingredient valued primarily for its high protein content.

- For dinner, we had chicken as our main protein with a side of vegetables.
- The chef suggested that lentils serve as an excellent plant-based protein for those looking to reduce their meat consumption without sacrificing nutrition.

## Examples

- Chicken and lentils are both high in protein.
- Athletes often consume a high-protein shake after training to help their muscles recover from intense exercise.
- While most people associate protein with animal products, a balanced plant-based diet can provide all the essential amino acids required for human health through a variety of grains and legumes.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.