Cru"ci*ble (kr&udd;"s&ibreve;*b'l), n. [LL. crucibulum a hanging lamp, an earthen pot for melting metals (cf. OF. croisel, creuseul, sort of lamp, crucible, F. creuset crucible), prob. of German origin; cf. OHG. krūsul, LG. krüsel, hanging lamp, kroos, kruus, mug, jug, jar, D. kroes cup, crucible, Dan. kruus, Sw. krus, E. cruse. It was confused with derivatives of L. crux cross (cf. Crosslet), and crucibles were said to have been marked with a cross, to prevent the devil from marring the chemical operation. See Cruse, and cf. Cresset.] 1. 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.

2. A hollow place at the bottom of a furnace, to receive the melted metal.

3. A test of the most decisive kind; a severe trial; as, the crucible of affliction.

• A cup-shaped piece of laboratory equipment used to contain chemical compounds when heating them to very high temperatures.
  
• A heat-resistant container in which metals are melted, usually at temperatures above 500°C, commonly made of graphite with clay as a binder.
  
• A very difficult and trying experience, that acts as a refining or hardening process.