Arduous vs. Onerous — What's the Difference?

Involving or requiring strenuous effort; difficult and tiring

Troublesome or oppressive; burdensome.

Demanding great effort or labor; difficult

(Law) Entailing more liabilities than benefits or imposing significant obligations.

Testing severely the powers of endurance; strenuous

Imposing or constituting a physical, mental, or figurative load which can be borne only with effort; burdensome.

Hard to traverse, climb, or surmount.

Burdensome; oppressive.

Needing or using up much energy; testing powers of endurance.

Not easily borne; wearing;

(obsolete) burning; ardent

Difficult or exhausting to traverse.

Steep and lofty, in a literal sense; hard to climb.

Attended with great labor, like the ascending of acclivities; difficult; laborious; as, an arduous employment, task, or enterprise.

Characterized by toilsome effort to the point of exhaustion; especially physical effort;

Taxing to the utmost; testing powers of endurance;

Difficult to accomplish; demanding considerable mental effort and skill;