The word "re-actor" can mean someone who responds or reacts to a situation. Synonyms for this could include responder, reactor, and quick-thinker. Another meaning of "re-actor" can refer to a device used for nuclear fission reactions. Synonyms for this definition could include nuclear reactor, atomic reactor, or power plant. Additionally, synonyms for "re-actor" could depend on the specific context of its usage, such as in theatre or film. In those cases, synonyms could include performer, actor, player, or artist. Overall, the definition and corresponding synonyms for "re-actor" can vary depending on the intended meaning and usage within a sentence.