Other forms: shrinkages
When something becomes smaller than it was before, that's shrinkage. You can see shrinkage in action when you accidentally put your favorite wool sweater in the dryer!
The process of shrinking, or the amount that something has shrunk, is shrinkage. You might notice the shrinkage of your hand-knit socks when you try to put them on your feet, or read about the shrinkage of the polar ice caps in school. Another meaning of this word is "loss of inventory due to theft or shoplifting." A store's shrinkage rate sometimes improves after they install security cameras.