[under one's belt] {adv. phr.}, {informal}
1. In your stomach; eaten; or absorbed.
* /Once he had a good meal under his belt, the man loosened his tie and fell asleep./* /Jones is talkative when he has a few drinks under his belt./
2. In your experience, memory or possession; learned or gotten successfully; gained by effort and skill.
* /Jim has to get a lot of algebra under his belt before the examination./* /With three straight victories under their belts, the team went on to win the championship./