As adjectives the difference between vigorous and relentless
is that vigorous is physically strong and active while relentless is unrelenting or unyielding in severity.
vigorous
English
Alternative forms
* vigourous
Adjective
(
en adjective)
Physically strong and active.
Rapid of growth
relentless
English
Adjective
(
en adjective)
Unrelenting or unyielding in severity
Unremitting, steady and persistent
Derived terms
* relentlessness