Anesthesia, or anaesthesia (see spelling differences; from Greek αν-, an-, "without"; and αἴσθησις, aisthēsis, "sensation"), traditionally meant the condition of having sensation (including the feeling of pain) blocked or temporarily taken away. It is a pharmacologically induced and reversible state of amnesia, analgesia, loss of responsiveness, loss of skeletal muscle reflexes or decreased stress response, or all simultaneously. This allows patients to undergo surgery and other procedures without the distress and pain they would otherwise experience...