Adamant

Adamant and similar words are used to refer to any especially hard substance, whether composed of diamond, some other gemstone, or some type of metal. Both adamant and diamond derive from the Greek word , ἀδάμαντος (adamas, adamantos), meaning "untameable". Adamantite and adamantium (a metallic name derived from the Neo-Latin ending -ium) are also common variants.

Adamantine has, throughout ancient history, referred to anything that was made of a very hard material. Virgil describes Tartarus as having a screeching gate protected by columns of solid adamantine (Aeneid book VI). Later, by the Middle Ages, the term came to refer to diamond, as it was the hardest material then known, and remains the hardest non-synthetic material known.

It was in the Middle Ages, too, that adamantine hardness and the lodestone's magnetic properties became confused and combined, leading to an alternate definition in which "adamant" means magnet, falsely derived from the Latin adamare, which means to love or be attached to. Another connection was the belief that adamant (the diamond definition) could block the effects of a magnet. This was addressed in chapter III of Pseudodoxia Epidemica, for instance.

Since the word diamond is now used for the hardest gemstone, the increasingly archaic term "adamant" has a mostly poetic or figurative use. In that capacity, the name is frequently used in popular media and fiction to refer to a very hard substance.

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