noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   The chemical element (symbol Rb) with an atomic number of 37. It is a soft, highly reactive alkali metal. uncountable
2. 2
   a soft silvery metallic element of the alkali metal group; burns in air and reacts violently in water; occurs in carnallite and lepidolite and pollucite wordnet
3. 3
   A single atom of this element. countable

Synonyms

All synonyms

atomic number 37goldironleadmetalrb

Example

More examples

"Lithium, sodium, potassium, rubidium, caesium and francium are alkali metals."

Etymology

A New Latin word derived by German chemist R. W. Bunsen in 1861, from Latin rūbidus (“red”) because its spectrum has two red lines.

Related phrases

rubidium auriderubidium chloriderubidium hydroxiderubidium nitraterubidium oxiderubidium-strontiumatomic number

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.