at cross purposes
US /æt krɔs ˈpɜrpəsɪz/
UK /æt krɔs ˈpɜrpəsɪz/

1.
各說各話, 誤解
if two people are at cross purposes, they think that they are talking about the same thing but are in fact talking about different things, with the result that they do not understand each other
:
•
I think we're talking at cross purposes; I meant next Tuesday, not this Tuesday.
我想我們是在各說各話;我指的是下週二,而不是這週二。
•
The two departments were constantly at cross purposes, leading to inefficiencies.
這兩個部門總是各行其是,導致效率低下。