On the other hand, the term "poliomyelitis" is the medical word for "infection ("-itis") of the gray matter of the spinal cord", ("polio-" = "gray", "myel-" means here "spinal cord", because bone marrow is either yellow or red, but not gray. Therefore the term "myel-" may not stand for "marrow" in this connection, but for "spinal cord" which has gray matter in its substance.)

Similarly the Greek word "neuron" was at one time in antiquity used to define not only a nerve, but also a tendon. Greek physicians soon established the term "tenon" for sinew (hence the English word "tendon"), keeping the word "neuron" for "nerve" exclusively.

Yet one term has survived as a misnomer in our medical vocabulary: "aponeurosis" (literally: "from a tendon"). The term "aponeurosis" is derived from the ancient usage of the word element "neuron" for "tendon", and it means: "a tendon-like sheet of connective tissue or extending band from a tendon", connecting muscle to bone or muscle to muscle, lacking any association to the meaning "nerve".

The term "neurosis" is also a misnomer but of a different origin, namely due to lack of differentiation of this psychic disorder from nervous system disease. We know now that it not to a disorder of the nervous system, but rather a psychiatric condition, often marked by depression and anxieties, but without loss of reality.