1. To have eaten or drunk something. Once I have some proper food under my belt, I'll be ready to tackle any work you can throw at me! My father could become quite nasty when he had a bit of booze under his belt. That's why he gave up drinking.

2. To have some achievement, accomplishment, or record attributed to one's career or reputation. The legendary batter had more than 2000 runs under his belt by the time he retired. As a pilot in training, it's always a relief to have your first real landing under your belt.

3. To have something learned or mastered. Once he had the proper technique under his belt, Jacques had no problem finishing the project on his own.