Fanatism is the act of being excessively enthusiastic about a particular thing or idea. When describing a person's fanaticism, it can be expressed in various ways, such as zeal, fervor, dedication, or obsession. These words reflect a strong passion, admiration, or commitment towards something or someone. On the other hand, fanaticism can also be associated with negative connotations, such as intolerance, extremism, dogmatism, or narrow-mindedness. These words suggest an unwavering adherence to a particular ideology or belief system, often to the point of disregarding differing opinions or perspectives. Overall, choosing an appropriate synonym for fanatism depends on the context and tone of the message.