The loss of feeling or sensation. With respect to surgery, means the loss of sensation of pain, as it is induced to allow surgery or other painful procedures to be performed. General: A state of unconsciousness, produced by anesthetic agents, with absence of pain sensation over the entire body and a greater or lesser degree of muscle relaxation. Local: Anesthesia confined to one part of the body. Spinal: Anesthesia produced by injection of a local anesthetic into the subarachnoid space around the spinal cord.