Interested in Language
This expression is defined the following way, in the Longman Dictionary of Contemporary English:
However, if I'm not mistaken, I've heard this expression used in different contexts. For example, suppose you're sitting on your couch and you realize you're tired. You're not working, but can you still say: "I'm beat, i'm calling it a day"?10 call it a day informal to decide to stop working, especially because you have done enough or you are tired : Come on, letís call it a day and go home.