Nowhere in this play is there of a mention of the word "crucible." So where exactly did that come from? And what in the world is a crucible, anyway?
It turns out the word has two definitions.
Humans Were Harmed in the Course of These Laboratory Tests
Let's tackle the first definition, shall we? A crucible is a piece of laboratory equipment used to heat chemical compounds to very high temperatures or to melt metal. It's a little container full of violent reactions. Seems like a pretty good metaphor for the violent hysteria that the little village of Salem contained during the witch trials. With all those folks jammed together in a tiny town, there were bound to be some hot tempers.
Yep, Salem became a crucible for many people living there... when they were brought before the religious court and accused falsely of being witches. If an accused person did not confess, she was hanged. If she did confess, she was spared death but marked for life as a person who worshiped the Devil. Classic Catch-22.
Under such conditions, several characters in this play—especially the central characters, John and Elizabeth Proctor—are forced to face their own internal demons, a process that ultimately leads to internal, spiritual transformation.
Trial By Fire
The term crucible can also be used metaphorically, which brings us to our next definition: a test or a trial. Folks use the term crucible to refer to a difficult test.
And there sure are a lot of tests going on in The Crucible. There are the tests to determine who's a witch. Then there are, quite literally, the trials the accused must undergo. And then, as we mentioned above, there are the more internal trials, where folks' deepest, most powerful beliefs are put to the test by their less-than-ideal circumstances.
Twentieth-Century Salem
The title (and the entire play) is also a metaphor for the anti-communist craze of America's Red Scare, led by Senator Joseph McCarthy. Thanks to the efforts of McCarthy's House Un-American Activities Committee, the whole United States became a "crucible" in which citizens' beliefs about what it meant to be American were deeply tested in the highest halls of government.