Wiktionary
a. 1 (context chemistry English) Not reactive; relatively inert. 2 (context psychology English) That does not respond to a stimulation.
WordNet
adj. not reacting chemically [ant: reactive]
not tending to react to stimulation [syn: unresponsive]
Usage examples of "unreactive".
He paused, searching for words as Spock remained as still and unreactive as the black stone surrounding them.
It is a highly unreactive metal, which I would expect to find uncombined and highly localized.
The features of Handir and the Humbled were as unreactive as engravings.
The gas is relatively unreactive, does not freeze out at Martian temperatures and cannot rapidly escape from the Martian exosphere.
A chemical bond known as the hydrogen bond has an energy appropriately intermediate between these unreactive and unstable alternatives.