Steadfast is a related term of untiring.
As adjectives the difference between steadfast and untiring
is that steadfast is fixed or unchanging; steady while untiring is not able to be tired; inexhaustible.
steadfast
English
Alternative forms
* stedfast (obsolete)
Adjective
(en-adj)
Fixed or unchanging; steady.
Firmly loyal or constant; unswerving.
Derived terms
* steadfastly
* steadfastness
untiring
English
Adjective
(-)
Not able to be tired; inexhaustible.
Unfailing; resolute.