To invent a story or an excuse. She had to make up a story to explain why she was late.
To reconcile or resolve a disagreement. After their argument, they decided to make up and be friends again.
To compensate for something missed or lost. He had to make up the missed classes by attending extra sessions.
To constitute or form a part of something. Women make up a significant portion of the workforce.
To apply cosmetics to one's face. She likes to make up before going out for the evening.