- any element having an atomic number higher than 103, the last of the actinide series. These superheavy, radioactive elements are extremely short-lived, and can only be created in the laboratory.
See also transuranic element.
Origin of transactinide element
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- any artificially produced element with an atomic number greater than 103
C20: from trans- + actinide
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012