That depends! The identity operator must map something from a space X to a space Y. This mapping might be continuous - which is the case if the identify operator is bounded - or discontinuous - if the identity operator is unbounded.

A solid cannot be bounded by one polygon. A solid bounded by polygons is called a polyhedron.

bounded signal

a bounded medium is a connection that used wires... the medium is the form of connection and bounded simply means that it is a wired connection!

Bounded MediaB: Bounded media are the physical links through which signals are confined to narrow path. Bounded media are made up of a external conductor(usually copper) bounded by jacket material. These are also called guided media.