eka-actinium

English

Etymology

From eka- +‎ actinium.

Noun

eka-actinium (uncountable)

1. (chemistry) unbiunium (element 121)
2. (chemistry) untriennium (dvi-lanthanum) (element 139)

Usage notes

This inconsistency, between referring to element 121 versus element 139, comes from the fact the elements beyond oganesson are not known, so it is unknown what element would be placed directly below actinium.