1. The figure in a plane bounded by two concentric circles.
2. Set of elements with two binary operations, which forms a commutative group with respect to the first operation, with second operation being associative and distributive versus the first.
- inner radius - promień wewnętrzny
- outer radius - promień zewnętrzny
- pierścień przemienny - commutative ring
- pierścien z jednością - ring with unity
- podpierścień - subring