A device for killing bacteria and other organisms on surgical supplies, bacteriology test tubes and Petri dishes etcetera, by steam at high temperature and pressure.

But take a look at Webster's 1913 definition:"

Autoclave
(Au"to*clave) n. [F., fr. Gr. a'yto`s self + L. clavis key.] A kind of French stewpan with a steam-tight lid. Knight.

The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.

autoclave

SYLLABICATION: au·to·clave
PRONUNCIATION: ôt-klv
NOUN: A strong, pressurized, steam-heated vessel, as for laboratory experiments, sterilization, or cooking.
ETYMOLOGY: French : Greek auto-, auto- + Latin clvis, key (from the fact that it is self-locking from the pressurization).

Notice AHD doesn't even mention surgical supplies, which
is its most important application.