beryllium

American  

[buh-ril-ee-uhm] / bəˈrɪl i əm /

noun

Chemistry.

1. a steel-gray, bivalent, hard, light, metallic element, the salts of which are sweet: used chiefly in copper alloys for better fatigue endurance, in springs, and in electrical contacts. Be; 9.0122; 4; 1.8 at 20° C.

---

beryllium British  

/ bɛˈrɪlɪəm /

noun

1. Former names: glucinum.   glucinium.  a corrosion-resistant toxic silvery-white metallic element that occurs chiefly in beryl and is used mainly in X-ray windows and in the manufacture of alloys. Symbol: Be; atomic no: 4; atomic wt: 9.012; valency: 2; relative density: 1.848; melting pt: 1289°C; boiling pt: 2472°C

---

beryllium Scientific  

/ bə-rĭl′ē-əm /

1. A hard, lightweight, steel-gray metallic element of the alkaline-earth group, found in various minerals, especially beryl. It has a high melting point and is corrosion-resistant. Beryllium is used to make sturdy, lightweight alloys and aerospace structural materials. It is also used as a neutron moderator in nuclear reactors. Atomic number 4; atomic weight 9.0122; melting point 1,278°C; boiling point 2,970°C; specific gravity 1.848; valence 2.

2. See Periodic Table

---

Etymology

Origin of beryllium

1860–65; < Latin bēryll ( us ) beryl + -ium

Example Sentences

Concentrations of beryllium, copper, chromium, nickel and lead in particular were significantly above established safety thresholds for marine life, prompting fears for the long-term health of fish, marine mammals and the marine food chain.

From Los Angeles Times • Mar. 20, 2026

To generate the required beam, scientists accelerated Mo-92 ions and fired them at a beryllium target, producing fast moving Mo-86 nuclei.

From Science Daily • Mar. 8, 2026

Other elements found in Ukraine include beryllium and uranium, which are both crucial for nuclear weapons and reactors.

From BBC • Apr. 30, 2025

Paul Bierman's laboratory at the University of Vermont dated the sample's last time near the surface in a different way, using rare radioactive isotopes of aluminum and beryllium.

From Salon • Jul. 23, 2023

“However, I think we have now pretty conclusive evidence on the point. . . We have observed neutrons from targets other than beryllium in just the amount we expected.”

From "Big Science" by Michael Hiltzik