Antonyms of adj unreactive

2 senses of unreactive

Sense 1
unreactive (vs. reactive) -- ((chemistry) not reacting chemically)

reactive (vs. unreactive) -- (participating readily in reactions; "sodium is a reactive metal"; "free radicals are very reactive")
        => activated, excited -- ((of e.g. a molecule) made reactive or more reactive)
        => labile -- ((chemistry, physics, biology) readily undergoing change or breakdown)
        => oxidizable -- (capable of undergoing a chemical reaction with oxygen)
        => thermolabile -- ((chemistry, physics, biology) readily changed or destroyed by heat)
        => unstable -- (highly or violently reactive; "sensitive and highly unstable compounds")

Sense 2
unreactive -- (not tending to react to stimulation)

INDIRECT (VIA insensitive) -> sensitive -- (responsive to physical stimuli; "a mimosa's leaves are sensitive to touch"; "a sensitive voltmeter"; "sensitive skin"; "sensitive to light")

Similarity of adj unreactive

2 senses of unreactive

Sense 1
unreactive (vs. reactive) -- ((chemistry) not reacting chemically)
       => inactive -- ((chemistry) not participating in a chemical reaction; chemically inert; "desired amounts of inactive chlorine")
       => inert, indifferent, neutral -- (having only a limited ability to react chemically; chemically inactive; "inert matter"; "an indifferent chemical in a reaction")
       => noble -- (inert especially toward oxygen; "a noble gas such as helium or neon"; "noble metals include gold and silver and platinum")
       => stable -- (not taking part readily in chemical change)

Sense 2
unreactive -- (not tending to react to stimulation)
       => insensitive (vs. sensitive) -- (not responsive to physical stimuli; "insensitive to radiation")