An imaginary rock or mineral of impenetrable hardness; a name given to the diamond and other substances of extreme hardness.
An embodiment of impregnable hardness.
Very difficult to break, pierce, or cut.
Firm; unshakeable; unyielding; determined.
A mineral water containing iron, a voguish general remedy during the 17th-19th century.
Containing dissolved salts of iron.
Tasting of iron, said of mineral water.