What is Paresis?

Legal Definition
Paresis is a condition typified by a weakness of voluntary movement, or partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it can also be used to describe the muscles of the eyes (ophthalmoparesis), the stomach (gastroparesis), and also the vocal cords (Vocal cord paresis). Neurologists use the term paresis to describe weakness, and plegia to describe paralysis in which all voluntary movement is lost. The term paresis comes from the Ancient Greek: πάρεσις "letting go" or "paralysis" from παρίημι "to let go, to let fall".
-- Wikipedia
Legal Definition
In medical jurisprudence. Progressive general paralysis, involving or lcadiog to the form of insanity known as "dementia paralytica." Popularly, but not very correctly, called "softening of the brain." See Insanity.
-- Black's Law Dictionary