radioaktiivisella
Radioaktiivisella is a Finnish grammatical form rather than a standalone concept. It is the adessive singular form of the adjective radioaktiivinen, which means radioactive. The form is used when describing something in a context that expresses location, presence, or association with radioactivity, typically in combination with a noun in the adessive case.
In Finnish, adjectives agree with the noun in number and case. Therefore radioaktiivinen becomes radioaktiivisella when
Radioaktiivisella serves as a descriptor rather than a stand-alone noun. The underlying noun form for the concept
See also: radioaktiivisuus, radioaktiivinen, ionisoiva säteily. In context, radioaktiivisella signals that the subject under discussion is