(1):
(n.) A hollow place at the bottom of a furnace, to receive the melted metal.
(2):
(n.) A vessel or melting pot, composed of some very refractory substance, as clay, graphite, platinum, and used for melting and calcining substances which require a strong degree of heat, as metals, ores, etc.
(3):
(n.) A test of the most decisive kind; a severe trial; as, the crucible of affliction.