Dutch word hardheid comes from Dutch hard, Dutch heid

Detailed word origin of hardheid

Dictionary entry	Language	Definition
hard	Dutch (nld)	(economics) (of a currency) strong, not easily devalued. (emotion) heartless, unsympathetic. (magnitude) harsh, heavy. (objects) hard, strong. (sound) loud. (water) hard, rich in calcium. Hard, difficult. Unquestionable, uncontestable (noise) loudly. (speed) fast, swiftly. Very.
heid	Dutch (nld)
hardheid	Dutch (nld)	Hardness.