hard as nail (noun) durability: sturdiness over time
Sinonime: baseness, cheapness, frivolousness, inconsequence, inconsiderableness, irrelevance, measliness, negligibility, negligible, negligibleness, paltriness, shabbiness, smallness, subordination, trifle, triviality, unimportance
Antonime: impermanency, poorness, unreliability,
weakness