Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage as well as motor. In the United States, roughly 1 in 50 people have been diagnosed with some form of permanent or transient paralysis. The word comes from the Greek παράλυσις, "disabling of the nerves", itself from παρά (para), "beside, by" and λύσις (lysis), "making loose". A paralysis accompanied by involuntary tremors is usually called "palsy".