The term anaesthesia comes from the Greek words “an” (meaning without) and “aisthesis” (meaning sensation). In medical terms, it refers to a loss or absence of feeling or awareness. An anaesthetic is a substance that causes this lack of sensation or feeling when administered during surgery or other procedures. It can be used to prevent pain and discomfort, as well as to induce unconsciousness so the patient does not feel any pain or remember the procedure.