A specimen is a single plant or animal which is an example of a particular species or type and is examined by scientists.

A specimen of something is an example of it which gives an idea of what the whole of it is like.

A specimen is a small quantity of someone's urine, blood, or other body fluid which is examined in a medical laboratory, in order to find out if they are ill or if they have been drinking alcohol or taking drugs.

You can use specimen to refer to someone who has a quality of a particular kind.