under one's belt

under (one's) belt

1. In one's scope of experience. Once you get a few more major league games under your belt, you'll feel more comfortable.
2. Ingested or consumed. He should be less cranky after he gets some food under his belt.
See also: belt

under one's belt

Experienced or achieved, as in Once a medical student has anatomy under her belt, she'll have much less to memorize. This metaphoric expression likens food that has been consumed to an experience that has been digested. [Colloquial; first half of 1800s]
See also: belt