reactionary Syllabification: (re·ac·tion·ar·y)Pronunciation: /rēˈakSHəˌnerē/Translate reactionary | into French | into German | into Italian | into Spanish Definition of reactionary adjective (of a person or a set of views) opposing political or social liberalization or reform. noun (plural reactionaries) a reactionary person. The ending of reactionary is spelled -ary.reactionary in other Oxford dictionaries Definition of reactionary in the British & World English dictionary