different between arduous vs relentless

English

Etymology

From Latin arduus (“lofty, high, steep, hard to reach, difficult, laborious”), akin to Irish ard (“high”).

Pronunciation

• (Received Pronunciation) IPA^(key): /???dju??s/, /???d??u??s/
• (US) IPA^(key): /????d??u?s/

Adjective

arduous (comparative more arduous, superlative most arduous)

1. Needing or using up much energy; testing powers of endurance.
   • For more quotations using this term, see Citations:arduous.
2. (obsolete) burning; ardent
   • 1805-1814, Dante, Henry Francis Cary (translator), The Divine Comedy

3. Difficult or exhausting to traverse.
   • 1999, Scott Ciencin, Mike Fredericks, Dinoverse:

     Mike looked up from the arduous mountain trail. They'd been climbing for five hours and he was beginning to feel irritable.

   • For more quotations using this term, see Citations:arduous.

Synonyms

• burdensome, demanding, exhausting, fatiguing, laborious, onerous, strenuous, strugglesome, wearisome

Derived terms

• arduousness

Related terms

• arduity

Translations

Further reading

• arduous in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913.
• arduous in The Century Dictionary, New York, N.Y.: The Century Co., 1911.
• arduous at OneLook Dictionary Search

English

Etymology

relent +? -less

Pronunciation

• IPA^(key): /???l?ntl?s/

Adjective

relentless (comparative more relentless, superlative most relentless)

1. Unrelenting or unyielding in severity.
2. Unremitting, steady and persistent.
   • 2016 January 31, "Is Huma Abedin Hillary Clinton’s Secret Weapon or Her Next Big Problem?," Vanity Fair (retrieved 21 January 2016):

     In Clintonworld, the reaction to Grassley’s relentless assault on Huma is one of resignation.

Derived terms

• relentlessness

Translations