As adjectives the difference between unbreakable and relentless
is that unbreakable is difficult to break and therefore able to withstand rough usage while relentless is unrelenting or unyielding in severity.
As a noun unbreakable
is something that cannot be broken.
unbreakable
English
Adjective
(
en adjective)
difficult to break and therefore able to withstand rough usage
(of a horse) not able to be broken in
Antonyms
*breakable
*fragile
Noun
(
en noun)
Something that cannot be broken.
relentless
English
Adjective
(
en adjective)
Unrelenting or unyielding in severity
Unremitting, steady and persistent
Derived terms
* relentlessness