noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   A radioactive isotope of uranium, ²³⁸₉₂U, having a half-life of 4.5 billion years; it accounts for about 99.3% of natural uranium. uncountable

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