say it: ree-AK-tiv
reactive is an adjective meaning "participating readily in reactions". It carries 2 recorded senses.
participating readily in reactions
“sodium is a reactive metal”
“free radicals are very reactive”
chemistry · physics
reacting to a stimulus
“the skin of old persons is less reactive than that of younger persons”
Definitions, synonyms and semantic relations for reactive come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.