v.1. To become completely frozen: The water in the ice trays hasn't frozen up yet.
2. To cause something to freeze completely: We froze up the water for ice cubes. Freeze the juice up and we'll have some frozen treats!
3. To become fixed in place or unable to move: The lock froze up due to rust. When I noticed that I was being watched, I froze up.
4. To cause something to become fixed in place or unable to move: The subzero temperatures froze up the water pipes. The rust froze the gears up.