arduous

As adjectives the difference between arduous and stressful

is that arduous is needing or using up much energy; testing powers of endurance while stressful is irritating; causing stress.

As a verb lumbered

is (lumber).

As an adjective arduous is

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

In obsolete|lang=en terms the difference between tortuous and arduous

is that tortuous is (obsolete) injurious; tortious while arduous is (obsolete) burning; ardent.

As adjectives the difference between tortuous and arduous

is that tortuous is twisted; having many turns; convoluted while arduous is needing or using up much energy; testing powers of endurance.

As adjectives the difference between arduous and fierce

is that arduous is needing or using up much energy; testing powers of endurance while fierce is extremely violent, severe, ferocious or savage.

As adjectives the difference between plodding and arduous

is that plodding is progressing slowly and laboriously while arduous is needing or using up much energy; testing powers of endurance.

As a verb plodding

is present participle of lang=en.

As a noun plodding

is slow, laborious progress.

As adjectives the difference between sluggish and arduous

is that sluggish is habitually idle and lazy; slothful; dull; inactive; as, a sluggish man while arduous is needing or using up much energy; testing powers of endurance.

In obsolete terms the difference between arduous and feeble

is that arduous is burning; ardent while feeble is to make feeble; to enfeeble.

As adjectives the difference between arduous and feeble

is that arduous is needing or using up much energy; testing powers of endurance while feeble is deficient in physical strength; weak; infirm; debilitated.

As a verb feeble is

to make feeble; to enfeeble.

In obsolete|lang=en terms the difference between arduous and hectic

is that arduous is (obsolete) burning; ardent while hectic is (obsolete) a flush like one produced by such a fever.

As adjectives the difference between arduous and hectic

is that arduous is needing or using up much energy; testing powers of endurance while hectic is pertaining to bodily reactions characterised by flushed or dry skin.

As a noun hectic is

(obsolete) a hectic fever.

As adjectives the difference between breathtaking and arduous

is that breathtaking is stunningly beautiful; amazing while arduous is needing or using up much energy; testing powers of endurance.

As adjectives the difference between backbreaking and arduous

is that backbreaking is of work, very physically tiring while arduous is needing or using up much energy; testing powers of endurance.