What is `polymorphic behavior` in Adaptor pattern?

According to Wiki https://en.wikipedia.org/wiki/Decorator_pattern#Usage

A decorator makes it possible to add or alter behavior of an interface at run-time. Alternatively, the adapter can be used when the wrapper must respect a particular interface and must support polymorphic behavior, and the Facade when an easier or simpler interface to an underlying object is desired.

I'm not getting it about polymorphic behavior. Where's polymorphic happened in Adaptor, isn't adaptor just transform one interface into another interface ?