Steadfastness is unwavering firmness of purpose. His steadfastness, praised for her steadfastness, steadfastness under pressure.
It is admiring and rather grave, and it belongs to loyalty tested over time. The Old English is stead plus fast, meaning fixed in place, which is the whole image.
1nounsteadfastnessUnwavering firmness of purpose.
“Her steadfastness during her husband's long illness impressed everyone who knew her.”
steadfastness is a firmness.
Old English stedefaestnes is stede, a place, plus faest, fixed.
Old English
stedefæstnes — steadfastness
Middle English
stedfastnesse
English, today
steadfastness
From Middle English stedfastnesse, stedefastnesse, from Old English stedefæstnes (“steadfastness”), equivalent to steadfast + -ness.
Etymology from Wiktionary, CC BY-SA