noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   Radon-219 (²¹⁹₈₆Rn; symbol An), an isotope of radon dated
2. 2
   any of a series of radioactive elements with atomic numbers 89 through 103 wordnet
3. 3
   Synonym of radon. obsolete
4. 4
   an radioisotope of radon with a half-life of about four seconds wordnet
5. 5
   An actinide dated

Synonyms

All synonyms

radon-219actineonactinideactinium emanationactinoidactinoid

Etymology

Contraction of actinium emanation.

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