Antipathy or animosity toward someone or something; ill feeling (the opposite of favorability).
あの政治家に対して多くの人が反感を持っている。
Many people feel antipathy toward that politician.
不公平な扱いに反感を覚えた。
I felt resentment at the unfair treatment.
彼の発言は同僚の反感を招いた。
His remarks provoked animosity among his coworkers.