Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun reactivity

2 senses of reactivity

Sense 1
responsiveness, reactivity -- (responsive to stimulation)
       => sensitivity, sensitiveness, sensibility -- ((physiology) responsiveness to external stimuli; the faculty of sensation; "sensitivity to pain")

Sense 2
reactivity -- (ready susceptibility to chemical change)
       => susceptibility, susceptibleness -- (the state of being susceptible; easily affected)