What does lactic mean?
Lactic is an adjective meaning “of or relating to milk,” especially in biological contexts, or “of or relating to lactic acid.” The most familiar use is in “lactic acid,” a compound produced when bacteria ferment the sugar lactose in milk. This acid is responsible for the tart flavor and thickened texture of foods such as yogurt and is also produced in muscles during intense exercise. The word is used in scientific, medical, and food-related language, including “lactic fermentation,” “lactic bacteria,” and “lactic acidosis.” Because its connection with both milk and muscle metabolism can make it seem broader than it is, it is best used when the milk or lactate association is relevant. In general contexts, “lactic” is more precise than vague terms such as “sour” when describing a biochemical or food process.
adjectiveRelating to milk or to lactic acid. In biological and biochemical contexts, it describes substances, processes, or effects associated with the production or action of lactic acid.
- Relating to milk or the milk-producing process.
- Relating to lactic acid, lactate, or fermentation involving lactic acid.
"The bacteria produced lactic acid through lactic fermentation, causing the milk to thicken and sour."
"Lactic bacteria ferment the lactose in milk and give yogurt its characteristic texture."
"The report described the athlete's condition as lactic acidosis following severe exertion."
Lactic acid is the substance that gives yogurt and sour milk their tart flavor, and it is also the acid linked to the fatigue and burning associated with strenuous exercise.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does lactic come from?
The word comes from Latin lact-, meaning “milk,” which was borrowed from Greek lakto-, likewise meaning milk. The adjective lactic developed in connection with substances and processes derived from milk, especially lactic acid, and later became associated more broadly with lactate biology and fermentation.
Related word forms
How lactic is actually used
Most common in technical, scientific, and food-related contexts. It is not normally used as a general synonym for sour.