Chronic Progressive Multiple Sclerosis (CPMS) is a largely outdated term that describes any form of progressive MS (forms of multiple sclerosis in which there is a gradual, irreversible worsening of symptoms).

Because there appear to be key differences in the the different forms of MS, it is now more usual to talk of Secondary Progressive, Primary Progressive or Progressive Relapsing MS.

MS Glossary
All About Multiple Sclerosis