A crucible is defined as a container that can withstand intense heat and also is a severe test, both of which apply to the subject of the play. Arthur Miller wrote "The Crucible" in 1953, depicting the events of the Salem witch trials of the mid to late 1600s.
In the 1950s, McCarthyism was rampant. It is defined as an intense campaign against alleged communists in the United States, and was compared to the Salem witch trials. Arthur Miller wrote his play "The Crucible" as an allegory of the movement, which prompted an investigation against him in 1956.
Because the play addresses the witch trials and the trials the accused suffered through, the title of "The Crucible" is a natural fit. The tests in the play that the accused endured had a goal to bring about a type of change, or to reveal that person's true colors. A direct comparison is the fact that quite often witches were burned at the stake, which is also in line with the word's definition. Arthur Miller writes the play in a manner that involves the audience. As observers, the audience is able to identify the motivation of the characters, then reevaluate as the play continues. In essence, each member of the audience decides for him or herself whether or not the character passes the test.