1) to invent (a story, lie, excuse, reason, etc.). 2) to resolve an argument or quarrel (not a separable verb when used like this). 3) to compensate for something. 1) I don't believe their story. I think they made it up. 2) Are they still fighting about that? I thought they had made up a while ago? 3) I didn't get anything accomplished yesterday. I'm going to have to work extra hard to make up for it today.