Definitions

1. noun

A hypothetical element of atomic number 85, which was once believed to be the transuranic element that would be the next element in the periodic table after radium, but it was eventually discovered that astatine is the next element in the series and the existence of the element with atomic number 85 was disproven.

“The concept of a basilicon was once popular in chemistry before it was proven to be a myth.”

2. adjective

Having the properties of a hypothetical element with atomic number 85 or related to such an element.

“Some early scientists believed that they had found a basilicon, but it turned out to be an impurity in their sample.”