beryllium

noun

be·​ryl·​li·​um bə-ˈri-lē-əm 

: a chemical element of the alkaline earth metal group with atomic number 4 that occurs naturally in minerals such as beryl and is steel-gray in color, light and strong but brittle, and is used chiefly as a hardening agent in alloys see Chemical Elements Table

Examples of beryllium in a Sentence

Recent Examples on the Web

But tests of seawater collected before and after the heavy rains that came in late January, after the fires abated, identified five heavy metals — beryllium, copper, chromium, nickel and lead — at levels significantly above established safety thresholds for marine life. —Corinne Purtill, Los Angeles Times, 28 Mar. 2025

Ukraine’s other deposits of beryllium and uranium could be used for nuclear power and weapons. —Laura Kelly, The Hill, 16 Feb. 2025

Emeralds are mainly made up of the mineral beryl, which is made from the elements beryllium, aluminum, silicon and oxygen. —Daniel Freedman, The Conversation, 4 Feb. 2025

The main feature is a deformable mirror, which is a thin, reflective surface that can be made from a variety of materials, including glass, beryllium, molybdenum, and composites. —Sidd Bikkannavar, IEEE Spectrum, 26 Feb. 2010

Word History

Etymology

New Latin, from Greek bēryllion

First Known Use

circa 1847, in the meaning defined above

Rhymes for beryllium

• concilium
• ileum
• lilium
• psyllium
• trillium
• penicillium
• verticillium

Kids Definition

beryllium

noun

be·​ryl·​li·​um bə-ˈril-ē-əm 

: a steel-gray light strong brittle toxic metallic element used chiefly to help harden alloys see element

Medical Definition

beryllium

noun

be·​ryl·​li·​um bə-ˈril-ē-əm 

: a steel-gray light strong brittle toxic bivalent metallic element used chiefly as a hardening agent in alloys

—symbol Be see Chemical Elements Table