crucible

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A vessel made of a refractory substance such as graphite or porcelain, used for melting and calcining materials at high temperatures.
2. n. A severe test, as of patience or belief; a trial. See Synonyms at trial.
3. n. A place, time, or situation characterized by the confluence of powerful intellectual, social, economic, or political forces: "Macroeconomics . . . was cast in the crucible of the Depression” ( Peter Passell).

Century Dictionary and Cyclopedia

1. n. A vessel or melting-pot for chemical purposes, made of pure clay or other material, as black-lead, porcelain, platinum, silver, or iron, and so baked or tempered as to endure extreme heat without fusing. It is used for melting ores, metals, etc. Earthen crucibles are shaped upon a potter's wheel with the aid of a templet or molding-blade, or under pressure in a molding-press. Metallic crucibles, especially those of platinum, are chiefly used in chemical analyses and assays.
2. n. A hollow place at the bottom of a chemical furnace, for collecting the molten metal.
3. n. Figuratively, a severe or searching test: as, his probity was tried in the crucible of temptation.

Wiktionary

1. n. chemistry A cup-shaped piece of laboratory equipment used to contain chemical compounds when heating them to very high temperatures.
2. n. A heat-resistant container in which metals are melted, usually at temperatures above 500°C, commonly made of graphite with clay as a binder.
3. n. The bottom and hottest part of a blast furnace; the hearth.
4. n. A very difficult and trying experience, that acts as a refining or hardening process.

GNU Webster's 1913

1. 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.
2. n. A hollow place at the bottom of a furnace, to receive the melted metal.
3. n. A test of the most decisive kind; a severe trial.

WordNet 3.0

1. n. a vessel made of material that does not melt easily; used for high temperature chemical reactions