noun Chemistry, Physics.
- a superheavy, synthetic, radioactive element with a very short half-life. Symbol: Bh; atomic number: 107.
- a transuranic element artificially produced in minute quantities by bombarding 204 Bi atoms with 54 Cr nuclei. Symbol: Bh; atomic no: 107Former names: element 107, unnilseptium
- A synthetic, radioactive element that is produced by bombarding bismuth with chromium ions. Its most long-lived isotopes have mass numbers of 261, 262, and 264 with half-lives of 11.8 milliseconds, 0.1 second, and 0.44 second, respectively. Atomic number 107. See Periodic Table.