The term epidural is often short for epidural anesthesia, a form of regional anesthesia involving injection of drugs through a catheter placed into the epidural space. The injection can cause both a loss of sensation (anaesthesia) and a loss of pain (analgesia), by blocking the transmission of pain signals through nerves in or near the spinal cord.
The epidural space (sometimes called the extradural space or peridural space) is a part of the human spine inside the spinal canal separated from the spinal cord and its surrounding cerebrospinal fluid by the dura mater.