According to the wiki answers, Anesthesia, or anaesthesia (see spelling differences; from Greek, an-, “without”; and, 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 fight-or-flight response, or all simultaneously. This allows patients to undergo surgery and other procedures without the distress and pain they would otherwise experience. An alternative definition is a “reversible lack of awareness,” including a total lack of awareness (e.g. a general anesthetic) or a lack of awareness of a part of the body such as a spinal anesthetic. The pre-existing wordanesthesia was suggested by Oliver Wendell Holmes, Sr. in 1846 as a word to use to describe this state.
It is the branch of medical science or specialty practice of physicians (anesthesiologists) or other clinicians such as Anesthetists that deal with providing anesthesia and anesthetics. Anesthesia is the blocking of pain. Anesthetics are drugs that block pain and/or put you in an unconscious or sedated state so that medical procedures and surgical procedures can be done.
When determining the meaning of a medical word you read the word starting with the suffix or ending then you read the prefix or beginning and then the root or middle of the word. Logy- is the suffix meaning the study of, an- is the prefix meaning without, and esthes/o- is the root word meaning sensation or feeling. So when you put those together the word means the study of being without feeling or sensation.
Lewis Satloff blog