crucible
n. countablen. a container used for melting metals at very high temperatures. It also describes a very difficult situation that forces someone to change or make a hard decision.
n. a vessel made of heat-resistant material used for high-temperature chemical reactions or melting metals. Figuratively, refers to a severe test or a situation in which different elements interact to produce something new.
The jeweler placed the gold into the ceramic crucible.
The intense pressure of the championship final acted as a crucible for the young athlete's character.
Historians often view the war as a crucible that forged a unified national identity from a collection of disparate and often conflicting regional interests.
From Latin crucibulum (“night-lamp, metallurgic melting-pot”), apparently a derivative of crux (“cross”), perhaps by analogy to thūribulum (“censer”) and suffix -bulum, or from crucio (“to torment”).
In its figurative sense, it is frequently used with the verb 'forge' or 'test'.