: a phosphoprotein of milk: such as
a
: one that is precipitated from milk by heating with an acid or by the action of lactic acid in souring and is used in making paints and adhesives
b
: one that is produced when milk is curdled by rennet, is the chief constituent of cheese, and is used in making plastics
Examples of casein in a Sentence
Recent Examples on the Web
An allergic reaction occurs when an individual's immune system reacts to proteins in a food—casein and whey, in the case of milk.
—
Hatty Willmoth, Newsweek, 21 Jan. 2025
This Al casein, largely present in mass-market dairy products, is toxic to the body, unlike A2 casein, which comes from the milk of goats, ewes and non-hybridized cows.
—Marie Bladt, Vogue, 24 Dec. 2024
The milk protein isolate includes both whey and casein, with casein making up 80% of the protein found in milk.
—Shushy Rita Setrakian Ms, Rd, Health, 9 Aug. 2024
An allergic reaction to milk is an immune response to casein and whey proteins in milk, that can occur within minutes of consuming milk or milk products, or after several days.
—Paul Du Quenoy, Newsweek, 9 Jan. 2025
See all Example Sentences for casein 
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Hatty Willmoth, Newsweek, 21 Jan. 2025
This Al casein, largely present in mass-market dairy products, is toxic to the body, unlike A2 casein, which comes from the milk of goats, ewes and non-hybridized cows.
—Marie Bladt, Vogue, 24 Dec. 2024
The milk protein isolate includes both whey and casein, with casein making up 80% of the protein found in milk.
—Shushy Rita Setrakian Ms, Rd, Health, 9 Aug. 2024
An allergic reaction to milk is an immune response to casein and whey proteins in milk, that can occur within minutes of consuming milk or milk products, or after several days.
—Paul Du Quenoy, Newsweek, 9 Jan. 2025
See all Example Sentences for casein
Dictionary Entries Near casein
Cite this Entry
“Casein.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/casein. Accessed 20 Feb. 2025.
Copy CitationKids Definition
casein
noun
ca·sein
ˈkā-ˌsēn 
kā-ˈsēn
1
: a phosphorus-containing protein that is separated from milk especially by the action of acid that is used in making paints and adhesives
2
: a phosphorus-containing protein that is produced when milk is made to form curds by rennet, that makes up a major part of cheese, and that is used in making plastics
Medical Definition
casein
noun
ca·sein
ˈkā-ˌsēn, ka-ˈsēn
: any of several phosphoproteins of milk: as
a
: one that occurs as a colloidal suspension in milk
called also caseinogen
b
: one that is produced when milk is curdled by rennet, is the chief constituent of cheese, and is used in making plastics
called also paracasein
Love words? Need even more definitions?
Merriam-Webster unabridged
Share