rubidium

noun

ru·​bid·​i·​um rü-ˈbi-dē-əm 

: a soft silvery metallic element of the alkali metal group that reacts violently with water and bursts into flame spontaneously in air see Chemical Elements Table

Examples of rubidium in a Sentence

Recent Examples on the Web

The rubidium signal suggests that these rocks ultimately originated from the core-mantle boundary. —David Bressan, Forbes.com, 23 May 2025

When Earth formed around 4.5 billion years ago, the rubidium was locked in the core together with gold and other precious metals. —David Bressan, Forbes.com, 23 May 2025

At the heart of their system is a proprietary quantum magnetometer, which measures the way an external field influences the spin of rubidium atoms, in a compact, lightweight package about the size of a Rubik’s cube. —The Physics Arxiv Blog, Discover Magazine, 22 Apr. 2025

The unique, patentable aspect of the project, Simon says, might be the use of a weakly acidic solution that pulls out only rubidium, or rubidium plus lithium. —IEEE Spectrum, 11 Feb. 2025

Word History

Etymology

New Latin, from Latin rubidus red, from rubēre

First Known Use

1861, in the meaning defined above

Rhymes for rubidium

• clostridium
• cranidium
• cymbidium
• iridium
• peridium
• presidium
• pygidium
• cryptosporidium
• idiom

Kids Definition

rubidium

noun

ru·​bid·​i·​um rü-ˈbid-ē-əm 

: a soft silvery metallic element that reacts violently with water see element

Medical Definition

rubidium

noun

ru·​bid·​i·​um rü-ˈbid-ē-əm 

: a soft silvery metallic element that decomposes water with violence and bursts into flame spontaneously in air

—symbol Rb see Chemical Elements Table