1. the former systematic name for the chemical element dubnium (atomic number 105)
Usage: chemistry; obsolete

Examples

• Unnilpentium was the temporary name given to element 105 before it was officially named dubnium.
• Scientists used the systematic name unnilpentium while the element’s discovery was being verified.
• The element formerly known as unnilpentium is now called dubnium in honor of the Joint Institute for Nuclear Research in Dubna.
• Unnilpentium follows the IUPAC naming convention for undiscovered or unconfirmed elements.
• Research papers from the 1980s often referred to element 105 as unnilpentium.