What does acidophilus mean?
Acidophilus refers to Lactobacillus acidophilus, a beneficial bacterium that naturally colonizes the human intestine and vagina, where it helps maintain a healthy microbial balance by producing lactic acid. The word also denotes milk that has been fermented with these bacterial cultures, a product popularized in the twentieth century for its supposed digestive benefits. In everyday usage, acidophilus appears most often in discussions of probiotics, yogurt, dietary supplements, and gut health, frequently mentioned alongside advice about restoring intestinal flora after antibiotic treatment. The name derives from Latin acidus ('sour') combined with Greek philos ('loving'), reflecting the organism's ability to flourish in acidic environments. Though primarily a scientific and commercial term rather than a literary one, acidophilus has entered common vocabulary through the wellness industry, making it a useful word for anyone navigating conversations about nutrition, fermentation, or microbiology.
A lactic-acid-producing bacterium, Lactobacillus acidophilus, occurring naturally in the human gut and used in fermented dairy products and probiotic supplements.
"Many yogurts are cultured with acidophilus to aid digestion."
Typically treated as uncountable; the rare plural 'acidophiluses' refers to individual bacterial cells.
Milk fermented with cultures of Lactobacillus acidophilus, consumed as a health food.
"He drank a glass of acidophilus each morning for its probiotic benefits."
Rarely used; acidophilus normally functions as an uncountable noun referring to the organism or product in general. The plural appears mainly in microbiological contexts denoting individual bacterial cells.
"The slide revealed numerous acidophiluses under high magnification."
The name literally means 'acid-loving' — this tiny gut dweller thrives in conditions that would kill most other microbes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of acidophilus
The term acidophilus combines the Latin adjective acidus, meaning sour or acidic, with the Greek element philos, meaning loving or fond of, so the name literally describes an organism that thrives in acid. It was coined in scientific Latin as the species epithet of Lactobacillus acidophilus, a bacterium first isolated from the human digestive tract around 1900. The same acid- plus -phil- construction gives English related terms such as acidophilic and acidophilous, while the -phil element appears more broadly in words like bibliophile and philosophy.
Related word forms
How acidophilus is actually used
Used almost exclusively in health, nutrition, and microbiology contexts; treated as an uncountable mass noun when referring to the organism or the product generally. The plural 'acidophiluses' exists for individual bacterial cells but is rare outside scientific writing.
Easily confused with acidophilus
Acidophilus is a beneficial bacterium, whereas acidosis is a medical condition in which body fluids contain too much acid.