Fanaticism/fəˈnætɪsɪzəm/ Definition 1 of 2Pro Tip 1/3Negative Connotation Fanaticism often implies harmful or extreme behavior, not just strong interest. His fanaticism about the cause led him to ignore his family. Pro Tip 2/3Beyond Passion 'Fanaticism' goes beyond being a fan; it involves excessive zeal. The crowd's fanaticism turned the rally into chaos. Pro Tip 3/3Common Collocations Commonly used with 'religious' or 'political' to describe extreme beliefs in these areas. Religious fanaticism can fuel dangerous conflicts.