strenuous

As adjectives the difference between strenuous and grueling

is that strenuous is urgent, ardent, zealous while grueling is .

As adjectives the difference between strenuous and backbreaking

is that strenuous is urgent, ardent, zealous while backbreaking is (figuratively) of work, very physically tiring.

As adjectives the difference between strenuous and tedious

is that strenuous is urgent, ardent, zealous while tedious is boring, monotonous, time consuming, wearisome.

As an adverb extremely

is (degree) to an extreme degree.

As an adjective strenuous is

urgent, ardent, zealous.

Powerful is a related term of strenuous.

As adjectives the difference between powerful and strenuous

is that powerful is having, or capable of exerting power, potency or influence while strenuous is urgent, ardent, zealous.

Stouthearted is a related term of strenuous.

As adjectives the difference between stouthearted and strenuous

is that stouthearted is brave, courageous and plucky while strenuous is urgent, ardent, zealous.

Manful is a related term of strenuous.

As adjectives the difference between manful and strenuous

is that manful is showing the characteristics considered typical of a man; macho or manly while strenuous is urgent, ardent, zealous.

Strenuous is a related term of unfathomable.

As adjectives the difference between strenuous and unfathomable

is that strenuous is urgent, ardent, zealous while unfathomable is impossible to fathom or understand; incomprehensible.

Courageous is a related term of strenuous.

As adjectives the difference between courageous and strenuous

is that courageous is of a person, displaying or possessing courage while strenuous is urgent, ardent, zealous.

As adjectives the difference between tenuous and strenuous

is that tenuous is thin in substance or consistency while strenuous is urgent, ardent, zealous.