Dubnium

noun

1. An artificially produced radioactive element with atomic number 105. The isotope with mass number 262 has the longest confirmed half-life (35 seconds), although longer half-lifes have been reported for some of its heavier isotopes. cross-reference: Periodic Table.
2. A transuranic chemical element (symbol Db) with atomic number 105.
3. A rejected name for rutherfordium.
4. a transuranic element