What is the medical term meaning abnormal tone?

Dystonia is an abnormal condition of muscle tone. Some specific types of dystonia include atonia (no muscle tone); hypotonia (too little muscle tone); and hypertonia (too much muscle tone). Increased muscle tension can cause the muscle to go into spasm. This is called tetany.

I don't know which term of muscle tone you are referring to, but I have cerebral palsy, so I can answer this easily. There are two terms that commonly describe abnormal muscle tone. One is hypertonia and the other is hypotonia. In hypertonia, too much tone enters the body. Muscles become stiff and sometimes stuck in certain positions (e.g. walking on the toes). In hypotonia, there is not enough tone to perform certain tasks. Muscles may act floppy or uncontrolled. Tone is very powerful, so a person who has problems typically cannot overcome it on their own.