What do we mean when we say, "I can't agree with you more or anymore?.'' Does it mean that we agree completely or entirely with a person's opinion or idea?
The precise wording for the idiomatic expression is "I can't agree with you
more," and it means precisely what you say it means: that the person agrees completely with another's opinion or idea. It's a very emphatic way of saying that you agree with someone, as contrasted by the plain agreement that's meant by simply saying "I agree with you." However, if we use "anymore" instead of "more"--"I can't agree with you
anymore"--the meaning is entirely different. It means that although the person had once agreed with another's opinion or idea, something happened that changed the mind of that person into disagreeing instead.