Steadfastness is a related term of allegiance.
As nouns the difference between steadfastness and allegiance
is that steadfastness is loyalty in the face of trouble and difficulty while allegiance is loyalty to some cause, nation or ruler.
steadfastness
English
Noun
Loyalty in the face of trouble and difficulty.
Steadfast resolution.
allegiance
Alternative forms
* allegiaunce (obsolete)
Noun
(
en noun)
Loyalty to some cause, nation or ruler.
Derived terms
* oath of allegiance
* pledge of allegiance
Synonyms
* fidelity, loyalty, adherence