just the opposite, esp. of something said or believed The evidence of history, on the contrary, shows that these ancient people had a very advanced culture.
Usage notes: often used to disagree with someone or something and to present new information
It's the opposite, as in Is his shoulder hurting?-On the contrary, it's all better, or We thought you didn't like opera.-On the contrary, I love it. This phrase, at first put as by or for or in the contrary, dates from the late 1300s; on has been used since the mid-1800s.