Emily Dickinson Lexicon

AD'A-MANT, n. [Gr. αδαμας; L. adamas; a word of Celtic origin; W. ehedvaen, a lodestone, from ehed, to fly or move, and vaen, or maen, a stone. Chaucer uses adamant for the lodestone. Romaunt of the Rose, lin. 1182. Ger. diamant, is adamant and diamond; Sp. diamante; Sw. damant; Fr. aimant, lodestone. See Diamond.]

A very hard or impenetrable stone; a name given to the diamond and other substances of extreme hardness. The name has often been given to the lodestone; but in modern mineralogy it has no technical signification.