反はん応のう性せいMeaningsNoun1. reactivityKanji used反be against応respond with action性nature (of a person)Composed of反はん応のうreaction; response; physical reaction (to a stimulus); observable response (of an organism); effect; changeNoun性せいnature (of a person); sex; gender; sex (i.e. sexual attraction, activity, etc.); -ty; -ity; -ness; -cyNoun