If you search this word, you will find many (a majority) of sites
that use it psychologically or as a psychiatric diagnosis.

It is a pretty old term, and I suspect it has an insurance code attached so that you and your doctor can get coverage for your visit. So may be used just for that purpose of convenience.

Motor neurons are basically myelinated (have an insulated axon) and as such are fast conducting nerves to muscles.

Sensory neurons are of 4 types, only one is heavily myelinated, and attached to tendons and providing proprioceptive information and fast conducting (telling the brain where you are in space). One sensory C fiber is totally unmyelinated and very slow conducting.
This graph shows the 4 types of sensory neurons outside the brain that provide information from the environment, and how they differ in myelination and speed of conductance:
Neuroscience For Kids - conduction velocity

Another graphic showing nerve cells and explanations:
Neuroscience For Kids - cells of the nervous system

As such the term you are asking about is just descriptive and not a diagnosis as such.