Describes something that is rounded and slightly sticking out; commonly used for a bulging belly. A mimetic word often used adverbially as 'pokkori'.
最近お腹がぽっこり出てきたので、運動を始めた。
My belly has been sticking out recently, so I started exercising.
ポッコリと膨らんだ箱が床に置かれていた。
A box that was bulging was placed on the floor.
ジャケットのポケットに財布がぽっこりはみ出している。
A wallet is sticking out of the jacket pocket.
お腹をへこませると、ぽっこりが少し目立たなくなる。
If you pull in your stomach, the bulge becomes a little less noticeable.