arduous

Arduous is a related term of troublesome.

As adjectives the difference between arduous and troublesome

is that arduous is needing or using up much energy; testing powers of endurance while troublesome is giving trouble or anxiety; vexatious; burdensome; wearisome.

Onerious is likely misspelled.

Onerious has no English definition.

As an adjective arduous is

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

As adjectives the difference between arduous and rigorous

is that arduous is needing or using up much energy; testing powers of endurance while rigorous is manifesting, exercising, or favoring rigour; allowing no abatement or mitigation; scrupulously accurate; exact; strict; severe; relentless; as, a rigorous officer of justice; a rigorous execution of law; a rigorous definition or demonstration.

Arduous is a related term of bewildering.

As adjectives the difference between arduous and bewildering

is that arduous is needing or using up much energy; testing powers of endurance while bewildering is very confusing, perplexing, or baffling, often due to a very large choice being available.

As a verb bewildering is

.

As a noun bewildering is

bewilderment.

Arduous is a related term of puzzling.

As adjectives the difference between arduous and puzzling

is that arduous is needing or using up much energy; testing powers of endurance while puzzling is difficult to understand or explain; enigmatic or confusing; perplexing.

As a verb puzzling is

.

As a noun puzzling is

time spent pondering something confusing.

As a verb beleaguer

is to besiege; to surround with troops.

As an adjective arduous is

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

As adjectives the difference between arduous and painful

is that arduous is needing or using up much energy; testing powers of endurance while painful is causing pain or distress, either physical or mental.

As adjectives the difference between arduous and impenetrable

is that arduous is needing or using up much energy; testing powers of endurance while impenetrable is not penetrable.

As adjectives the difference between arduous and complex

is that arduous is needing or using up much energy; testing powers of endurance while complex is made up of multiple parts; composite; not simple.

As a noun complex is

a problem.

As a verb complex is

to form a complex with another substance.