: 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
As the bacteria produce lactic acid, the milk becomes more acidic, which causes its proteins — called casein — to stop floating freely and link together into a microscopic network.
—
Samantha Agate, Charlotte Observer, 23 May 2026
That shift triggers casein proteins, which normally float freely, to link into a microscopic network that traps water, fat and nutrients.
—Samantha Agate, Kansas City Star, 23 May 2026
Those trials examined the effectiveness of different types of protein (whey, milk, casein, collagen, meat, soy, rice, oat, and dietary protein) in combination with and separate from physical exercise (resistance training, aerobic exercise, and multicomponent training).
—Malissa Rodenburg, Health, 15 May 2026
Meanwhile, casein is a slow-digesting protein but provides a sustained release of amino acids into the blood sugar.
—Kirsten Nunez, Martha Stewart, 2 May 2026
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Samantha Agate, Charlotte Observer, 23 May 2026
That shift triggers casein proteins, which normally float freely, to link into a microscopic network that traps water, fat and nutrients.
—Samantha Agate, Kansas City Star, 23 May 2026
Those trials examined the effectiveness of different types of protein (whey, milk, casein, collagen, meat, soy, rice, oat, and dietary protein) in combination with and separate from physical exercise (resistance training, aerobic exercise, and multicomponent training).
—Malissa Rodenburg, Health, 15 May 2026
Meanwhile, casein is a slow-digesting protein but provides a sustained release of amino acids into the blood sugar.
—Kirsten Nunez, Martha Stewart, 2 May 2026
See All Example Sentences for casein
Cite this Entry
“Casein.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/casein. Accessed 28 May. 2026.
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
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