cross purposes
noun /ˌkrɒs ˈpɜːpəsɪz/
/ˌkrɔːs ˈpɜːrpəsɪz/
[plural]- if two people are at cross purposes, they do not understand each other because they are talking about or aiming at different things, without realizing it
- I think we're talking at cross purposes; that's not what I meant at all.