iodine-125 iodine • iodine-131 · · · Info · Definitions · Characters · · iodine-125 · · Text Common · · Latin · · Scripts 10 · · Length 3 · · Syllables Definitions · · · (noun) 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. · · Noun Definition 1 Characters · · - hyphen-minus U+002D 1 digit one U+0031 2 digit two U+0032 5 digit five U+0035 d latin small letter d U+0064 e latin small letter e U+0065 i latin small letter i U+0069 n latin small letter n U+006E o latin small letter o U+006F