Unrelenting is a related term of abiding.
As adjectives the difference between unrelenting and abiding
is that
unrelenting is not relenting; having no pity; not being or becoming lenient, mild, gentle, or merciful; unyielding; inflexibly rigid; hard; stern; cruel while
abiding is continuing]] or [[persist|persisting in the same state; lasting; enduring .
As a noun abiding is
the action of one abides; the state of an abider .
As a verb abiding is
.