"Osteoarthritis" is derived from the Greek word "osteo", meaning "of the bone", "arthro", meaning "joint", and "itis", meaning inflammation, although many sufferers have little or no inflammation. A common misconception is that OA is due solely to wear and tear, since OA typically is not present in younger people. However, while age is correlated with OA incidence, this correlation merely illustrates that OA is a process that takes time to develop. There is usually an underlying cause for OA, in which case it is described as secondary OA. If no underlying cause can be identified it is described as primary OA. "Degenerative arthritis" is often used as a synonym for OA, but the latter involves both degenerative and regenerative changes.