The word "most monomaniacal" refers to a person who is excessively obsessed with a single topic or idea. The opposite of this word would be someone who is multifaceted, well-rounded, or versatile. Antonyms for "most monomaniacal" could include words such as broad-minded, diverse, balanced, eclectic, varied, adaptive, and well-rounded. A person who is not monomaniacal would have an open mind and be receptive to different perspectives and ideas. They would be flexible and adaptable, able to navigate different situations and approaches. In contrast, a monomaniacal person would be rigid and inflexible, unable to deviate from their fixation.