v.1. To cause the elements of something to be intermingled: Mix up the eggs and sugar before you pour them into the flour. Mix the batter up thoroughly before pouring it into the pan.
2. To prepare something by mixing: I mixed some eggs up for breakfast. I mixed up a cake for her birthday.
3. To confuse someone; confound someone: His explanation just mixed me up more. The confusing directions mixed up all the party guests.
4. To mistake something or someone for something or someone else: I always mix up the twins. I mixed the twins up because they were wearing the same thing.
5. To involve or implicate someone in the activities of someone or something, especially something negative: Don't mix yourself up with that crowd. She mixed him up in the whole mess. He got mixed up with the wrong people.
6. To increase the volume of some component of an electrical or audio signal relative to other components: Your singing sounds too quiet—we should mix it up. Mix up the microphones when the announcer begins speaking.