1. something achieved and now part of your experience
I need to get some more experience under my belt
To 'have something under your belt' means you have achieved it, experienced it or to have acquired knowledge or skills in that area. "I have two MA's and an MBA under my belt." "She has seven years' experience in communications under her belt." This is quite an informal expression but you can hear it used in professional and social contexts. To 'have something under your belt' can also mean to have consumed it. "He usually likes to have dinner under his belt before he gets down to business."