unrelenting
UK: ˌʌnrɪˈlɛntɪŋ | US: ˌʌnrɪˈlɛntɪŋ
adj. not yielding in strength, severity, or determination; persistent
adj. refusing to relent or show mercy; harsh
The word "unrelenting" combines the negative prefix "un-" (Old English "un-," meaning "not") with the verb "relent" (from Latin "re-" + "lentare," meaning "to bend or soften"). The suffix "-ing" turns it into an adjective. Historically, "relent" implied softening one's stance, so "unrelenting" literally means "not softening" — capturing the idea of unwavering persistence or severity.
The unrelenting rain caused severe flooding in the coastal town.
She faced the challenges with unrelenting determination.
His unrelenting criticism demoralized the team.
The desert sun was unrelenting, with no shade in sight.
Despite injuries, the athlete maintained an unrelenting pace.