A paralytic is any drug that causes a patient's muscles to completely relax so that the patient is unable to move the muscle. They work by preventing muscles from receiving the chemical signals that make them contract. They are often used in surgery to prevent muscles from spasming when cut, thus making the surgeon's job easier. Tubocurarine is one of the best known of the paralytics.
It should be noted that patients given paralytics can still feel pain, even though they cannot move in response.
In One Day, One Room, House deliberately injects a patient who is making a commotion in the clinic (the result of a cockroach biting the inside of his ear) with a paralytic merely in order to keep him quiet.