Parkinson's disease, also known as Parkinsonism or PD, is a degenerative disorder of the nervous system that affects movement. It is named after its discoverer, James Parkinson. While there aren't many synonyms for the name of the disease, there are a few other terms that are related to Parkinson's. For instance, there is Parkinson's syndrome, which is a cluster of symptoms that resemble Parkinson's disease but may have a different cause. There is also Parkinsonian tremor, which is a tremor (involuntary shaking) that resembles the tremor associated with Parkinson's. Additionally, some people use the term "shaking palsy" to refer to Parkinson's disease because one of its main symptoms is tremors.