selenium

[ si-lee-nee-uhm ]

nounChemistry.

a nonmetallic element chemically resembling sulfur and tellurium, occurring in several allotropic forms, as crystalline and amorphous, and having an electrical resistance that varies under the influence of light. Symbol: Se; atomic weight: 78.96; atomic number: 34; specific gravity: (gray) 4.80 at 25°C, (red) 4.50 at 25°C.

Origin of selenium

<New Latin (1818) <Greek selḗn(ē) moon + New Latin -ium-ium; named in allusion to its similarity to tellurium

Words Nearby selenium

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use selenium in a sentence

The selenium browser that ran for seven days, for example, clicked on more than 900 Google ads, and almost 1,200 ads in all.
This tool lets you confuse Google’s ad network, and a test shows it works | Konstantin Kakaes | January 6, 2021 | MIT Technology Review
“This proposed settlement will hold the company to account for its selenium pollution and helps fund an environmental project that benefits the Tug River,” said Karan Ireland, the West Virginia Sierra Club’s senior campaign representative.
A Coal Company Owned by This Billionaire Governor Has Pledged to Stop Breaking Pollution Laws | by Ken Ward Jr. | December 4, 2020 | ProPublica
He was also the person who first identified silicon, selenium, thorium, and serium.
After Dominick | J. J. Berzelius | November 7, 2008 | THE DAILY BEAST
(a) Organic selenium compounds were reviewed and their properties examined critically with those of allied compounds.
Synthesis of 2-methyl-4-selenoquinazolone, 2-phenylbenzoselenazole, and its derivatives | Y-Gwan Chen
(d) Two series of azo dyes of selenium have been prepared and have been shown to possess a marked tinctorial value.
Synthesis of 2-methyl-4-selenoquinazolone, 2-phenylbenzoselenazole, and its derivatives | Y-Gwan Chen

Since Berzelius published the first resume of the chemistry of selenium, in 1818, many articles have appeared in this field.
Synthesis of 2-methyl-4-selenoquinazolone, 2-phenylbenzoselenazole, and its derivatives | Y-Gwan Chen
No attempt has ever been made to compile a bibliography of selenium organic compounds.
Synthesis of 2-methyl-4-selenoquinazolone, 2-phenylbenzoselenazole, and its derivatives | Y-Gwan Chen
The general conception of selenium is that it is a comparatively rare element.
Synthesis of 2-methyl-4-selenoquinazolone, 2-phenylbenzoselenazole, and its derivatives | Y-Gwan Chen

British Dictionary definitions for selenium

selenium

/ (sɪˈliːnɪəm) /

noun

a nonmetallic element that exists in several allotropic forms. It occurs free in volcanic areas and in sulphide ores, esp pyrite. The common form is a grey crystalline solid that is photoconductive, photovoltaic, and semiconducting: used in photocells, solar cells, and in xerography. Symbol: Se; atomic no: 34; atomic wt: 78.96; valency: –2, 4, or 6; relative density: 4.79 (grey); melting pt: 221°C (grey); boiling pt: 685°C (grey)

Origin of selenium

C19: from New Latin, from Greek selēnē moon; named by analogy to tellurium (from Latin tellus earth)

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for selenium

selenium

[ sĭ-lē′nē-əm ]

A nonmetallic element that occurs in a gray crystalline form, as a red powder, or as a black glassy material. It is highly photosensitive and can be used to convert light into electricity. Its ability to conduct electricity also increases with higher exposure to light. For these reasons selenium is used in photocopying technology, photography, and solar cells. Atomic number 34; atomic weight 78.96; melting point 217°C; boiling point 684.9°C; specific gravity (gray) 4.79; (red) 4.5; (black) 4.28; valence 2, 4, or 6. See Periodic Table.

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