protein

noun, often attributive pro·tein \ ˈprō-ˌtēn also ˈprō-tē-ən \
Updated on: 10 Dec 2017

Definition of protein

1 : any of various naturally occurring extremely complex substances that consist of amino-acid residues joined by peptide bonds, contain the elements carbon, hydrogen, nitrogen, oxygen, usually sulfur, and occasionally other elements (such as phosphorus or iron), and include many essential biological compounds (such as enzymes, hormones, or antibodies)
2 : the total nitrogenous material in plant or animal substances

Examples of protein in a Sentence

  1. You need more protein in your diet.

  2. These foods are an excellent source of protein.

  3. These foods have all of the essential proteins.

Recent Examples of protein from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'protein.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of protein

French protéine, from Late Greek prōteios primary, from Greek prōtos first — more at prot-

Other Biochemistry Terms


PROTEIN Defined for English Language Learners

protein

noun

Definition of protein for English Language Learners

  • : a substance found in foods (such as meat, milk, eggs, and beans) that is an important part of the human diet


PROTEIN Defined for Kids

protein

noun pro·tein \ ˈprō-ˌtēn \

Definition of protein for Students

: a nutrient found in food (as meat, milk, eggs, and beans) that is made up of many amino acids joined together, is a necessary part of the diet, and is essential for normal cell structure and function

Medical Dictionary

protein

noun, often attributive pro·tein \ ˈprō-ˌtēn , ˈprōt-ē-ən \

medical Definition of protein

1 : any of numerous naturally occurring extremely complex substances (as an enzyme or antibody) that consist of amino acid residues joined by peptide bonds, contain the elements carbon, hydrogen, nitrogen, oxygen, usually sulfur, and occasionally other elements (as phosphorus or iron), that are essential constituents of all living cells, that are synthesized from raw materials by plants but assimilated as separate amino acids by animals, that are both acidic and basic and usually colloidal in nature although many have been crystallized, and that are hydrolyzable by acids, alkalies, proteolytic enzymes, and putrefactive bacteria to polypeptides, to simpler peptides, and ultimately to alpha-amino acids
2 : the total nitrogenous material in plant or animal substances; especially : crude protein


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