noun. 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.
- metallic element
noun. geological dating based on the proportions of radioactive rubidium into its decay product strontium; radioactive rubidium has a half-life of 47,000,000,000 years.
- geological dating
Example sentences of the word rubidium
1. Noun, singular or mass
If your PET scan is the rubidium type, you can't eat or drink anything but water for three hours before the scan.
2. Verb, non-3rd person singular present
Discovered in 1861, rubidium readily forms compounds with many other elements, such as oxygen and nitrogen.