What does "steeliness" mean?

toughness, hardness or durability resembling (or likened to) that of steel.

Steeliness

Common synonyms include: callousness, concentration, constancy, density, inflexibility, intransigence.

noun

noun ·Rare ·Advanced level

Noun

1
toughness, hardness or durability resembling (or likened to) that of steel. uncountable
"He had a steeliness of eye that tended to cow people who acted tough."

"He had a steeliness of eye that tended to cow people who acted tough."

From steely + -ness.