Quick answer
Anesthesia is the state — the loss of sensation. An anesthetic is the substance that produces it. You are given an anesthetic and you are then under anesthesia. Britain spells both with an extra a: anaesthesia, anaesthetic.
The core difference
A condition and the agent that causes it.
- anesthesia — the state of being without sensation.
- anesthetic — the drug or agent that produces it.
- anesthetist / anesthesiologist — the clinician who administers it; the titles differ by country.
The spelling
American English drops the a: anesthesia. British English keeps it: anaesthesia. The same pattern runs through pediatric/paediatric and fetus/foetus, all reflecting American simplification of the Greek and Latin digraphs.
The word
From Greek an- (without) plus aisthesis (sensation) — literally without feeling. The term was proposed in 1846 for the newly demonstrated surgical use of ether.
This page explains the words. It is not medical guidance.
Frequently asked questions
Which one is the drug?
The anesthetic. Anesthesia is the state it produces.
Why do British and American spellings differ?
American English simplified the Greek digraph, giving anesthesia; British English kept anaesthesia. The same applies to paediatric and foetus.
What does the word literally mean?
Without sensation, from Greek an- and aisthesis. It was coined in 1846 for the surgical use of ether.
