What does selenium mean?
Selenium is a chemical element, symbol Se, and an essential trace nutrient for humans and animals. It occurs in soil, plants, food, and the bodies of animals, and its concentration varies according to geology and agriculture. The body needs small amounts for functions involving the thyroid, immune system, and cellular protection, while too little can contribute to disorders such as Selenium deficiency, and excessive exposure may cause toxicity. Selenium also has important industrial uses: it is used in glassmaking, metallurgy, semiconductors, and photovoltaic cells. The word appears most often in scientific, medical, nutritional, and environmental discussions. In dietary contexts, it can name the nutrient, a food source, or a supplement, although the chemical element is the dominant sense.
nounA chemical element of group 16 of the periodic table, with the symbol Se and atomic number 34, occurring in several allotropic forms. It is also an essential trace nutrient for humans and animals and is used in metallurgy, glassmaking, semiconductors, and dietary supplements.
- The chemical element selenium, symbol Se, a nonmetal found in minerals, soils, foods, and certain industrial materials.
- Selenium as an essential trace nutrient obtained from food or supplements, or as a dietary preparation supplying it.
"A balanced diet can provide selenium, which supports normal thyroid and immune function."
"The laboratory tested the soil for selenium because grazing animals in the region showed signs of deficiency."
"She checked the label before taking selenium supplements to make sure she was not exceeding the recommended dose."
Usually uncountable; the plural is rare and used mainly when referring to distinct samples or forms.
"The researchers compared seleniums obtained from three different geological samples."
Selenium is named after the Moon, yet it can be both an essential trace nutrient and a toxic excess in the body.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does selenium come from?
The name selenium was coined in the early 19th century by Swedish chemist Jöns Jacob Berzelius for a newly identified element. It was formed from Greek selēnē, meaning “moon,” with the element's association reflected in related names such as selenite and selenology. The moon-based name contrasts with tellurium, whose name comes from the Latin word for “earth.”
How selenium is actually used
Selenium is primarily a scientific and nutritional term. In medicine and dietetics it may refer to the nutrient itself or to a supplement containing it; technical contexts generally use the symbol Se.
Easily confused with selenium
Selenium is a chemical element, whereas selenite is a mineral and also the name of a selenium-containing oxyanion, depending on context.
Selenium and tellurium are both group 16 elements, but selenium is a nonmetal and tellurium is a metalloid.