ununseptium

[ uhn-uh n-sep-tee-uh m ]
/ ˌʌn ənˈsɛp ti əm /

noun Chemistry, Physics.

a superheavy, synthetic, radioactive element with a short half-life. Symbol: Uus; atomic number: 117.
Also called element 117.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019