noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   The radioactive isotope of iodine, ¹²⁵₅₃I, having a half-life of 59 days; used as a radiation therapy. uncountable
2. 2
   light radioactive isotope of iodine with a half-life of 60 days; used as a tracer in thyroid studies and as a treatment for hyperthyroidism wordnet

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