Anaesthesia is a word derived from the Greek, meaning 'without sensation'. Anaesthesia may be applied to the whole body, when it is known as general anaesthesia, or to part of the body, when it is known as regional or local anaesthesia. All of these techniques involve giving specific drugs that interfere with the transmission of nervous impulses so as to reduce sensation. ‘Anaesthetic’ is the term applied to some or all of the drugs used to produce anaesthesia and is also used to describe the whole process. For example, one might say, ‘Mary had a general anaesthetic.’